CN113519098A - Coherent terahertz magnon lasers and coherent terahertz communication systems - Google Patents

Abstract

An apparatus for generating coherent terahertz radiation is provided. In one example, the device includes one or more multi-layered tunable microcolumns. Next, the multilayer tunable microcolumn may include a substrate, a bottom electrode, an underlayer of ferromagnetic material, further including a Magnon Gain Medium (MGM) coupled to the bottom electrode, a tunnel junction coupled to the ferromagnetic material, a spin injector coupled to the tunnel junction, a pinning layer coupled to the spin injector, a reference layer coupled to the pinning layer, and a top electrode. In one example, the receiving cavity encloses at least one of the plurality of layers of tunable microcolumns. In one example, the storage chamber surrounds the receiving chamber.

Description

Coherent terahertz magnon laser and coherent terahertz communication system

Cross Reference to Related Applications

The present application claims priority from U.S. non-provisional patent application serial No. 16/655,472 entitled "coheren tert ahertz MAGNON LASER AND coheren tert ahertz communica SYSTEM" filed on 17.10.2019 AND U.S. provisional patent application No. 62/822,284 entitled "coheren tert ahertz MAGNON LASER AND coheren tert ahertz communica SYSTEM" filed on 22.3.2019. This application is also a continuation-in-part application entitled "turbo multilizayer ahertz MAGNON GENERATOR" U.S. patent application No. 16/245,224 filed on 10.1.2019 and claiming priority therefrom. This application is also a continuation-in-part application No. 16/245,247 entitled "terabertz MAGNON generating transformer combining polymeric laser OF SINGLE terabertz MAGNON LASERS" filed on 10.1.2019 and claiming priority thereto. The entire contents of the above-identified applications listed herein are incorporated by reference.

Technical Field

The present invention relates to the field of magnon lasers for generating terahertz radiation.

Background

Terahertz (THz) radiation is an electromagnetic radiation in the frequency range of 0.1THz to 30THz, occupying the portion of the electromagnetic spectrum between the microwave band and the infrared band.

The energy of a terahertz photon is less than the energy of an optical photon. This is why the terahertz wave can penetrate deep into the substance through which the optical wave cannot penetrate. At terahertz frequencies, the molecules vibrate. This is why terahertz waves are useful in molecular research.

In fact, the unique rotational and vibrational response of molecules in the terahertz range provides information that is not typically present in optical, X-ray, and Nuclear Magnetic Resonance (NMR) images. Terahertz waves can easily penetrate and inspect the interior of most dielectric materials, which are opaque to visible light and have low contrast to X-rays, making them useful as a source of complementary imaging.

For example, terahertz waves maintain reasonable penetration depths in certain common materials, such as clothing, plastic, wood, sand, and soil. Thus, terahertz technology has the potential to detect materials that are encased or embedded with these explosives because explosives have unique terahertz spectral characteristics compared to surrounding materials. The spectrum fingerprint of the explosive material can be expected in a terahertz waveband, and terahertz imaging can be applied to landmine detection. However, at present, there is still a lack of efficient, compact solid state sources in the spectral range of 0.1-30 THz.

In fact, broadband pulsed terahertz sources are typically based on exciting different materials with ultrashort laser pulses. Several different mechanisms have been developed to generate terahertz radiation, including photo-carrier acceleration in photoconductive antennas, second-order nonlinear effects in electro-optic crystals, and the like.

For narrow-band terahertz sources, solid-state lasers are generally considered. They are based on inter-band transitions or inter-sub-band transitions in narrow-gap semiconductors, i.e. transitions in quantum confined structures (e.g. nanostructures), between restricted conduction or valence states. To obtain terahertz radiation from direct interband transitions requires a near zero gap semiconductor. For intersubband transitions, conventional wide gap materials can be used, but require precise complex structures. At present, it is feasible to construct a multiple quantum well semiconductor structure for laser emission.

Quantum cascades (quantum cascades) consist of repeating structures, where each repeating unit consists of one injector and one active region. In the active region, there is population inversion, and the electrons transition to a lower energy level, emitting photons of a particular wavelength. Kohler et al (R.Kohler et al, Nature 417,156(2002)) designed terahertz quantum cascade lasers operating at 4.4 THz. The laser consists of a total of 700 multiple quantum wells and exhibits pulsed operation at a temperature of 10K. For comments, see, e.g., B Ferguson and x. -c.zhang, nat. matter,26 (2002).

Recent advances in QCL generators have been reported by Manijeh Razeghi et al in Photonics Spectra, 12 months 48-51 (2016). The authors used a non-linear mixture of two QCLs. However, the use of non-linear mixers introduces inherent limitations. In fact, nonlinear QCL mixers are very complex devices (each such QCL comprises a plurality of barrier layers and a plurality of well layers, and has to be manufactured with an accuracy of up to 0.1 nm), with low output power in the continuous state (these devices reach a power output of up to 0.5 milliwatts only in the pulsed state); and has very limited adjustability in the (2-4.45) THz range.

AdTech Optics are located in California Industrial City, and innovative QC lasers have been developed and produced since 2005. QCL by adech is intended to cover most of the mid-infrared spectrum, from λ 3.8 μm (78THz) to λ 12.5 μm (23.9 THz). Almost all AdTech QCLs operate continuously at room temperature and can be designed to operate at a single frequency by using distributed feedback waveguide fabrication. However, AdTech's QCLs are only mechanically tunable, which makes these QCLs impractical for most applications including spectroscopy, communications, etc., to name a few.

Coherent terahertz magnon lasers can generate coherent radiation in the terahertz spectrum.

Coherent communication systems in terahertz spectroscopy can be used for many unique applications including, but not limited to, transmitting, receiving, and reading received terahertz holographic images.

Such terahertz holographic images can be used to encode secret information, including security codes that cannot be read by any other means, unless another terahertz magnon laser is used, such holographic images can be illuminated at the receiving end at the same terahertz frequency as recorded at the transmitting end of such coherent terahertz communication systems.

Disclosure of Invention

An apparatus for generating coherent terahertz radiation is provided. In one example, the device includes one or more multilayer tunable microcolumns (multilayer tunable microcolumns). In turn, the multilayer tunable microcolumn may include a substrate, a bottom electrode, a bottom layer of ferromagnetic material further including a Magnon Gain Medium (MGM) coupled to the bottom electrode, a tunnel junction (tunnel junction) coupled to the ferromagnetic material, a spin injector (spin injector) coupled to the tunnel junction, a pinning layer (pinning layer) coupled to the spin injector, a reference layer coupled to the pinning layer, and a top electrode. In one example, the receiving cavity encloses at least one of the plurality of layers of tunable microcolumns. In one example, the storage chamber surrounds the receiving chamber. This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the technology and together with the description, serve to explain the principles of the technology:

FIG. 1 depicts a cross-sectional view of a tunable multilayer terahertz magnon laser with a RUDERMAN-KITTEL-KASUYA-YOSIDA (RKKY) pinning layer for purposes of the present technique, the tunable multilayer terahertz magnon laser including a substrate, a bottom electrode, an underlayer, a tunnel junction, a spin injector, a pinning layer, a reference layer, and a top electrode.

FIG. 2 illustrates the dependence of the RUDERMANAN-KITTEL-KASUYA-YOSIDA (RKKY) interaction on the spacer layer thickness of ruthenium (Ru) for the purposes of the present technique.

Figure 3 shows the electron spectrum and generation of an unbalanced magnon in a semimetal for the purposes of the present technique.

FIG. 4 depicts a design of a tunable terahertz magnon laser with a tunnel junction for the purposes of the present technique.

FIG. 5 illustrates a voltage-based continuous tuning mechanism for a tunable terahertz magnon laser with the tunnel junction of FIG. 4 for the purposes of the present technique.

FIG. 6 illustrates an example device in accordance with an aspect of the subject disclosure.

FIG. 7 illustrates an exemplary method for generating unbalanced magnons in a magnon gain medium that would result in the generation of terahertz radiation.

Fig. 8 and 9 illustrate equations for magnon generation.

Fig. 10 illustrates another example apparatus in accordance with an aspect of the subject disclosure.

FIG. 11 is a front view of a terahertz generator for the purposes of the present technique that includes a plurality of single terahertz magnon lasers, each such single terahertz magnon laser also including a single multilayer column.

FIG. 12 illustrates a front view of a terahertz generator for purposes of the present technique that includes a plurality of single terahertz magnon lasers, each such single terahertz magnon laser further including a single multilayer column, and a terahertz transparent medium separating at least two such single multilayer columns.

FIG. 13 shows a top view of a terahertz generator for the purposes of the present technique that includes a plurality of single terahertz magnon lasers, each such single terahertz magnon laser further including a single multilayer column, and a terahertz transparent medium filled between such single multilayer columns.

FIG. 14 illustrates a terahertz coherent communication system configured to form, transmit, receive, and read holographic images in the terahertz spectrum for the purposes of the present technology.

Detailed Description

Reference will now be made in detail to embodiments of the present technology, examples of which are illustrated in the accompanying drawings. While the technology will be described in conjunction with various embodiments, it will be understood that they are not intended to limit the technology to these embodiments. On the contrary, the present technology is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the various embodiments as defined by the appended claims.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the presented embodiments. It will be apparent, however, to one skilled in the art that the presented embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the presented embodiments.

In one embodiment of the present technology, FIG. 1 depicts a cross-sectional view of a tunable multilayer terahertz magnon laser 10. For the purposes of the present technique, the tunable multilayer terahertz magnon laser 10 includes a substrate 12, a bottom electrode 14, an underlayer 16, a tunnel junction 18, a spin injector 20, a pinning layer 22, a reference layer 24, and a top electrode 28. In one embodiment, pinning layer 22 may also comprise a RUDERMAN-KITTEL-KASUYA-YOSIDA (RKKY) pinning layer. The single multi-layer pillar 26 includes the bottom layer 16, the tunnel junction 18, the spin injector 20, the pinned layer 22, the reference layer 24, and the top electrode 28. In one embodiment, the spin injector 20 may be, for example, a top layer. In another embodiment, the bottom electrode 14 may be a ground electrode.

In embodiments of the present technology, substrate 12 (of FIG. 1) comprises gallium arsenide (GaAs).

Gallium arsenide (GaAs) is a compound of gallium and arsenic. It is a group III-V direct band gap semiconductor with a sphalerite crystal structure. Gallium arsenide is used to fabricate monolithic microwave integrated circuits.

GaAs is commonly used as a substrate material for the epitaxial growth of other group III-V semiconductors, including: indium gallium arsenide, aluminum gallium arsenide, and the like.

GaAs can be manufactured by using Molecular Beam Epitaxy (MBE). MBE can be in, for example, high or ultra-high vacuum (10)^-8-10^-12) Carried out in a tray.

In one aspect, the deposition rate of MBE (typically less than 3,000 nm/hour) may allow for epitaxial growth of the film. These deposition rates generally require a better proportional vacuum to achieve the same impurity levels as other deposition techniques. The highest purity of the grown film can be achieved without carrier gases and ultra-high vacuum environment.

In solid source MBE, elements such as gallium and arsenic in ultra pure form are heated in a separate quasi-Knudsen effusion cell (quasi-Knudsen effusions cells) or electron beam evaporator until they start to sublimate slowly. The gaseous elements then condense on the chip where they can react with each other. In the case of gallium and arsenic, single crystal gallium arsenide is formed. When using evaporation sources such as copper or gold, gaseous elements impinging on the surface may be attracted (e.g., after a time window, impinging atoms will jump around the surface) or reflected. Atoms on the surface may also desorb (desorb).

Controlling the temperature of the source will control the rate at which material impinges on the surface of the substrate, and the temperature of the substrate will affect the rate of jumping or desorption. The term "beam" means that the evaporated atoms do not interact with each other or with the vacuum chamber gases before reaching the chip, because the mean free path of the atoms is long.

In one embodiment of the present technique, substrate 12 (of FIG. 1) comprises aluminum oxide (Al)₂O₃)。

In another embodiment of the present technique, substrate 12 (of FIG. 1) comprises aluminum nitride (AlN).

In yet another embodiment of the present technique, substrate 12 (of FIG. 1) comprises indium tin oxide (InTnO).

Indium Tin Oxide (ITO) is a ternary composition consisting of indium, tin and oxygen in varying proportions. Depending on the oxygen content, it can be described as a ceramic or an alloy. Indium tin oxide is commonly encountered together as an oxygen-saturated composition formulated as 74% In, 18% O by weight₂And 8% Sn. Oxygen saturated compositions are so typical that unsaturated compositions are referred to as oxygen deficient ITO. It is clear and colorless in thin layers, while it is light yellow to gray in bulk form. In the infrared region of the spectrum, it acts as a metalloid mirror.

Indium tin oxide is one of the most widely used transparent conductive oxides because it has two main properties: electrical conductivity and optical transparency, and it can be easily deposited as a thin film. As with all transparent conductive films, a compromise must be made between conductivity and transparency, since increasing the thickness and increasing the concentration of charge carriers increases the conductivity of the material, but decreases its transparency. Indium tin oxide films are most commonly deposited on the surface by physical vapor deposition. Electron beam evaporation or a series of sputter deposition techniques are often used.

In yet another embodiment of the present technique, the substrate 12 (of FIG. 1) comprises silicon (Si).

Silicon is a chemical element, denoted as Si, with an atomic number of 14. A hard and brittle crystalline solid with a bluish-gray metallic luster is a tetravalent metalloid. It is a member of group 14 of the periodic Table of elements, with carbon above and germanium, tin, lead and titanium in the lower part. It is quite inert, although not as active as germanium, but has a strong chemical affinity for oxygen. Therefore, it was produced in 1823 by

The Jakob Berzelius was first prepared and characterized in pure form.

Silicon is the eighth most common element in the universe by mass, but rarely appears as a pure element in the earth's crust. It is most widely distributed in the form of various forms of silica (silica) or silicates in dust, sand, asteroids and planets. Over 90% of the crust consists of silicate minerals, making silicon the second most abundant element in the crust next to oxygen (about 28% by mass). Highly purified silicon is used for integrated circuits.

In another embodiment of the present technique, the substrate 12 (of FIG. 1) comprises silicon on sapphire (SoS).

Silicon On Sapphire (SOS) is a heteroepitaxial process for integrated circuit fabrication, consisting of a process on sapphire (Al)₂O₃) A thin layer of silicon (typically less than 0.6 μm) grown on the chip.

SOS is a part of the silicon-on-insulator (SOI) family of CMOS technologies. Generally, high-purity artificially grown sapphire crystals are used. Silicon is typically deposited on a heated sapphire substrate by decomposition of silane gas (SiH 4). Sapphire has the advantage that it is an excellent electrical insulator to prevent radiation-induced stray currents from spreading to nearby circuit elements. SOS faces early challenges in commercial manufacturing due to difficulties in manufacturing the very small transistors used in modern high density applications. This is because the SOS process causes the formation of dislocations, twinning (twinning), and stacking faults (stacking faults) due to the lattice difference between sapphire and silicon. In addition, there is some contamination of the silicon with aluminum (a p-type dopant) in the silicon of the substrate closest to the interface.

Applications of epitaxial growth of silicon on sapphire substrates for the fabrication of MOS devices involve silicon purification processes that can reduce crystal defects caused by the mismatch between sapphire and silicon lattices. For example, the SP4T switch from Peregrine Semiconductor is formed on an SOS substrate, where the final thickness of silicon is approximately 95 nm. Silicon is recessed in the region outside the polysilicon gate stack by poly oxidation and further recessed to a thickness of approximately 78nm by a sidewall spacer formation process.

In yet another embodiment of the present technique, substrate 12 (of FIG. 1) comprises magnesium oxide (MgO).

Magnesium oxide (MgO) or magnesium oxide is a white hygroscopic solid mineral that naturally exists in the form of periclase and is the source of magnesium. It has an empirical formula for MgO, from Mg₂(Positive ion) and O₂(negative ions) are composed of crystal lattices bonded together by ionic bonds. Magnesium hydroxide forms (MgO + H) in the presence of water₂ O→Mg(OH)₂) But the reaction can be reversed by heating to separate the water.

Magnesium oxide has historically been referred to as magnesia alba (literally meaning white mineral from magnesium oxide-other sources refer to magnesia alba as MgCO₃) To distinguish it from magnesia negra, a black mineral containing what is now called manganese. Although "magnesium oxide" is commonly referred to as MgO, magnesium peroxide MgO₂Also known as a compound. Prediction of MgO from evolving crystal structure₂Thermodynamically stable at pressures above 116GPa (gigapascals), a brand new semiconductor suboxide Mg₃O₂Is thermodynamically stable above 500 GPa. Because of its stability, MgO is used as a model system for studying the vibration characteristics of crystals. Magnesium oxide is produced by calcining magnesium carbonate or magnesium hydroxide.

In one embodiment of the present technology, still referring to fig. 1, the bottom electrode 14 is selected from the group consisting of: cobalt iron alloy (Co)_0.5 Fe _0.5) (ii) a Silver (Ag); gold (Au); platinum (Pt); cobalt (Co); palladium (Pd); titanium (Ti); and titanium Tungsten (TiW).

Each of these materials may be deposited on the substrate by Molecular Beam Epitaxy (MBE) (see discussion above) or by sputter deposition.

Sputter deposition is a Physical Vapor Deposition (PVD) method of thin film deposition by sputtering. This involves ejecting material from a "target" as a source onto a "substrate", such as a silicon chip. Re-sputtering (re-sputtering) is the re-emission of deposited material by ion or atom bombardment during the deposition process. The sputtered atoms ejected from the target have a broad energy distribution, typically up to tens of eV (100,000K). Sputtered ions (typically only a small fraction of the ejected particles are ionized-about 1%) can fly in a straight trajectory from the target and give an energetic impact on the substrate or vacuum chamber (resulting in re-sputtering).

Alternatively, at higher pressures, ions collide with gas atoms acting as moderators (modifiers) and move diffusively, reaching the substrate or vacuum chamber wall and condense after undergoing random walk (random walk). By varying the background air pressure, the entire range from high energy ballistic impact to low energy thermalization motion can be entered.

The sputtering gas is typically an inert gas, such as argon. To achieve efficient momentum transfer, the atomic weight of the sputtering gas should be close to the target atomic weight, so neon is the preferred sputtering light element, and krypton or xenon is used for the sputtering heavy element. Reactive gases may also be used to sputter the compounds. Depending on the process parameters, the compound may be formed on the target surface, in-flight, or on the substrate. The availability of many parameters to control sputter deposition makes it a complex process, but also allows experts to control the growth and microstructure of the thin film to a large extent.

An important advantage of sputter deposition is that even very high melting point materials are easily sputtered, which is problematic or impossible to evaporate in a resistive evaporator or Knudsen cell. The composition of the sputter-deposited film is close to that of the source material. This difference is due to the fact that different elements diffuse differently due to their different masses (light elements are more easily deflected by the gas), but the difference is constant.

Sputtered films generally have better adhesion to the substrate than evaporated films. The target contains a large amount of material and requires no maintenance, so the technique is suitable for ultra-high vacuum applications.

The sputter source contains no thermal components (they are usually water-cooled to avoid heating) and is compatible with reactive gases such as oxygen. Sputtering can be done from top to bottom, while evaporation must be done from bottom to top. Advanced processes such as epitaxial growth are possible.

Some disadvantages of the sputtering process are that it is more difficult to combine this process with lift-off for film build-up. This is because the diffusion transport, characteristic of sputtering, makes complete shadows (shadow) impossible. Therefore, the direction of the atoms cannot be completely restricted, which may lead to contamination problems. Furthermore, active control of layer-by-layer growth is difficult compared to pulsed laser deposition, with inert sputtering gases entering the growing film as impurities.

Pulsed laser deposition is a variation of the sputter deposition technique, in which sputtering is performed using a laser beam. The role of the sputtering and resputtering ions and background gases is well studied in pulsed laser deposition processes.

Sputtering sources typically employ magnetrons (magnetrons) that use strong electric and magnetic fields to confine charged plasma particles to a position close to the surface of a sputtering target. In the magnetic field, electrons follow a helical path around the magnetic field lines, with more ionizing collisions with gaseous neutrals near the target surface than would otherwise occur. (as the target material is consumed, the surface of the target may appear to have a "race track" erosion profile.)

The sputtering gas is typically an inert gas, such as argon. The additional argon ions generated due to these collisions result in a higher deposition rate. The plasma can also be maintained at a lower pressure in this way. Sputtered atoms are neutrally charged and are therefore not affected by magnetic traps (magnetic traps).

The use of radio frequency sputtering, in which the sign of the anode-cathode bias is varied at a high rate (typically 13.56MHz), can avoid charge build-up on the insulated target. Rf sputtering works well for producing highly insulating oxide films but adds to the cost of the rf power supply and impedance matching network. Stray magnetic fields leaking from the ferromagnetic target can also interfere with the sputtering process. It is often necessary to compensate using specially designed sputter guns with exceptionally strong permanent magnets.

In one embodiment of the present technique, still referring to fig. 1, the bottom layer 16 is selected from the group consisting of: chromium dioxide (CrO)₂) (ii) a Half-metal ferromagnetic oxide Sr₂FeMoO₆(ii) a Heusler (Heusler) alloy Co₂MnGe; heusler alloy Co₂Mnsi (cms); heusler alloy Co₂Fesi (cfs); heusler alloy Co₂Mnsn (cms); and heusler alloy Co₂FeAl_0.5Si_0.5(CFAS)。

For example, in a recent paper published in Nat commun, 5 months and 30 days 2014; m. Jourdan et al, "Direct adherence of half-compatibility in the Heusler compound Co2 MnSi", Co₂The MnSi samples were prepared in a synchrotron radiation ultraviolet emission spectroscopy (SRUPS) chamber consisting of a sputtering chamber, a Molecular Beam Epitaxy (MBE) chamber, and a helium discharge lamp (21.2 eV) equipped and a hemispherical energy analyzer (energy resolution) with a multichannel spin filter

Sielman function S ═ 0.42 ± 0.05) in an ultra-high vacuum cluster. First, an epitaxial buffer layer of Heusler compound Co2MnGa (30nm) was grown on a MgO (100) substrate by Radio Frequency (RF) sputtering at room temperature. By an optimized additional annealing process, an L21 sequence (order) was obtained at 550 ℃, as shown by high energy electron diffraction (RHEED) and X-ray diffraction (XRD). Co2MnSi (70nm) was radio frequency sputtered on top at room temperature. Under the induction of the buffer layer, the Co2MnSi film already shows a certain degree of L2 when being deposited₁Surface sequence. The sequence was improved by additional annealing as evidenced by RHEED on the surface of the film.

In one embodiment of the present technique, still referring to fig. 1, the tunnel junction 18 is selected from the group consisting of: magnesium oxide (MgO); alumina (Al)₂O₃) (ii) a And spinelMgAl₂O₄。

For example, it is disclosed in Journal of Physics D by S Vangelista et al: in Applied Physics, volume 46, paper of 48, "Low-temperature chemical layer deposition of MgO thin films on Si", a magnesium oxide (MgO) film is formed by using bis (cyclopentadienyl) magnesium and H₂The O precursor is grown by atomic layer deposition in a wide deposition temperature window of 80-350 ℃. MgO film with 0.12nm cycle^-1Is deposited on HF-last Si (100) and SiO₂On a/Si substrate. The structure, morphology and chemical properties of the synthesized MgO thin film were studied by X-ray reflectance, grazing incidence X-ray diffraction, time-of-flight secondary ion mass spectrometry and atomic force microscopy measurements. In addition to good chemical uniformity and a polycrystalline structure with a thickness exceeding 7nm, the MgO layer is characterized by a sharp interface with the substrate and a limited surface roughness. CV measurements were performed on Al/MgO/Si MOS capacitors with MgO thicknesses ranging from (4.6-11) nm, which allowed the dielectric constants (κ) to 11 to be determined. The Co layer is deposited by chemical vapor deposition in direct contact with MgO without vacuum break (base pressure 10)^-5-10^-6Pa) was grown. The grown Co/MgO stack showed a sharp interface with no inter-diffusion of elements between the layers. C-V and I-V measurements have been performed on Co/MgO/Si MOS capacitors. The dielectric properties of MgO are not affected by the process of further Co deposition.

In one embodiment of the present technique, still referring to fig. 1, the spin injector 20 is selected from the group consisting of: chromium dioxide (CrO)₂) (ii) a Half-metal ferromagnetic oxide Sr₂FeMoO₆(ii) a Heusler alloy Co₂MnGe; heusler alloy Co₂Mnsi (cms); heusler alloy Co₂Fesi (cfs); heusler alloy Co2 MnSn; and heusler alloy Co₂FeAl_0.5Si_0.5(CFAS)。

For example, the paper "Structural and magnetic properties and channel magnetic properties for Co" in K Inomata et al₂(Cr,Fe)Al and Co₂FeSi full-Heusler alloys "published in Journal of Physics D: applied Physics, Vol.39, No. 5, investigation of Co₂(Cr_{1_x}Fex) Al (x is more than or equal to 0 and less than or equal to 1) and Co₂Structure and magnetization of FeSi perhheusler alloys. Deposition of thin films on thermally oxidized Si (SiO) by ultra-high vacuum sputtering at various temperatures₂) And an MgO (001) single crystal substrate. After deposition at Room Temperature (RT), the film was also post annealed. By using Co₂YZ (20nm)/Al (1.2nm) -oxide/Co₇₅Fe₂₅(3nm)/IrMn (15nm)/Ta (60nm) Stack Structure A magnetic tunnel junction with all Huesler alloy electrodes was fabricated and etched 10 using electron beam lithography and Ar ion²μm²Micro-machining of junction area of (1), wherein Co₂YZ stands for Co₂(Cr_{1_x}Fex) Al or Co₂FeSi. The tunnel barrier is formed by deposition of 1.2nm aluminum followed by plasma oxidation in the chamber. X-ray diffraction revealed either A2 or B2 structures, depending on the heat treatment conditions and the substrate, but not Co₂(Cr_{1--_x}L2 of Fex) Al (x is more than or equal to 0 and less than or equal to 1) film₁And (5) structure. However, when Co is used₂When an FeSi thin film is deposited on an MgO (001) substrate at a high temperature of more than 473K, L2 is obtained₁And (5) structure. For using Co₂(Cr_0.4Fe_0.6) The junction of the Al electrode had a maximum Tunnel Magnetoresistance (TMR) of 52% at room temperature and 83% at 5K. But instead use a circuit having L2₁Co of structure₂The junction of the FeSi electrode exhibited 41% TMR at room temperature and 60% at 5K, which can be improved by using a buffer layer to reduce Co₂Lattice mismatch between FeSi and MgO (001) substrates.

In one embodiment of the present technology, still referring to FIG. 1, the pinning layer 22 is selected from the group consisting of: iridium manganese chromium (IrMnCr); iridium manganese (IrMn); nickel manganese (NiMn); nickel manganese chromium (NiMnCr); nickel manganese iron (NiMnFe); nickel manganese iridium (NiMnIr); nickel manganese palladium (NiMnPd); nickel manganese platinum (NiMnPt); nickel manganese rhodium (NiMnRh); platinum manganese (PtMn) and nickel manganese ruthenium (NiMnRu).

For example, in the paper "Magnetic Tunnel Junction Materials for Electronic Applications" published by JM Slaurighter et al at JOM-e,52(6) (2000), ferromagnetic films are pinned in contact with Antiferromagnetic (AF) films due to exchange coupling. For uncoupled, free ferromagnetic films, the magnetic orientation of the film shows a hysteresis behavior pointing in the direction of the finally applied saturation field. If a saturation field is applied and then removed again, the magnetic orientation of the free film will be in the direction of the field. If the direction of the applied saturation field is reversed and removed again, the magnetic orientation of the film will be reversed. Thus, in zero applied field, either direction is possible. Ferromagnetic films pinned by the AF layer exhibit similar behavior but with an offset. In zero field, the ferromagnetic films will be aligned in one direction. Exchange coupling between the ferromagnetic layer and the AF layer causes the ferromagnetic layers to align preferentially in one direction at their mutual interface. For the memory device in question, this preferential alignment or pinning is used to lock one layer in a fixed direction. Most of the work in AF-pinning materials and other areas of the field has centered around manganese-based antiferromagnetic materials such as platinum-manganese, iridium-manganese, rhodium-manganese and iron-manganese. Platinum-manganese is a particularly interesting pinning material because it remains antiferromagnetic at relatively high temperatures. Unlike many commonly used AF alloys, as-deposited platinum-manganese is not AF. Instead, such materials must be post-annealed, resulting in a phase transition from face-centered cubic (f.c.c.) to face-centered tetragonal (f.c.t.) crystal structures. The f.c.t. phase of platinum-manganese is AF and pins the adjacent ferromagnetic film. The pinning strength increases with annealing time. The shift and broadening of the nickel-iron hysteresis loop in the annealed material is a characteristic of the pinned ferromagnetic film. Once pinned, the exchange bias causes the magnetic orientation of the film to be in one direction of zero applied field.

In one embodiment of the present technique, still referring to FIG. 1, the pinned layer 22 further comprises a RuDERMAN-KITTEL-KASUYA-YOSIDA (RKKY)) nonmagnetic pinned layer.

As shown in FIG. 2, the RKKY interaction 100 exhibits an anti-iron magnetic polarity (e.g., at location 102 of the RKKY interaction 100) for a ruthenium spacer having a layer thickness of about 8 angstroms. For reference, see S.S.P.Parkin, "Spin Engineering of the Ruderman-Kittery-Kasuya-Yosida far-field function in the ruminum," Phys. revision B44 (13), 1991.

In one embodiment of the present technology, the magnetization direction of the spin injector 20 may be antiparallel to the magnetization direction of the underlayer 16 to allow maximum minority current to be injected into the underlayer 16, which includes the magnon gain medium, using a ruthenium spacer with a thickness of about 8 angstroms as the pinned layer (pinned layer 22 of FIG. 1). The injection of the maximum minority current will substantially simplify reaching the point of magnon excitation.

In one embodiment of the present technique, still referring to FIG. 1, the reference layer 24 comprises a ferromagnetic material for selecting the orientation of the underlayer 16 in a particular direction.

In embodiments of the present technique, the reference layer 24 (e.g., the free layer) may be formed by using CFA (B2-ordered Co)₂FeAl). Please refer to the following documents: hiroaki Sukegawa, Zhenchao Wen, Kouta Kondou, Shinya Kasai, Seiji Mitani, Koichiro Inomata; application physical flash 100,182403 (2012); "Spin-transfer switching in full-Heusler Co2FeAl-based magnetic tunnel junctions".

In one embodiment of the present technique, still referring to fig. 1, the top electrode 28 is selected from the group consisting of: cobalt iron alloy (Co)_0.5 Fe _0.5) (ii) a Silver (Ag); gold (Au); platinum (Pt); cobalt (Co); palladium (Pd); titanium (Ti); and titanium Tungsten (TiW). Each of these materials can be deposited by MBE or sputtering.

In one embodiment of the present technique, still referring to FIG. 1, both the spin injector 20 and the pinned layer 22 are replaced by a single layer electron injector. In this embodiment, the electron injector is selected from the group consisting of: a metal; a metal alloy; a ferromagnetic metal; and ferromagnetic alloys.

In embodiments of the present technology, a terahertz magnon laser 10 (FIG. 1) generates terahertz radiation based on the magnon laser effect. For reference, see U.S. patent nos.: 7,430,074, respectively; 7,508,578, respectively; 9,136,665. In an aspect, a voltage bias 74 may be applied to the bottom electrode 14 and the top electrode 28 to facilitate generation of terahertz radiation.

The nature of terahertz radiation based on the magnon laser effect is as follows. The Magnon Gain Medium (MGM) comprises a conduction band divided into two sub-bands separated by an exchange gap, a first sub-band with a free-wheeling direction up and a second sub-band with a free-wheeling direction down (not shown).

In the case of conventional lasing, if an atom is already in an excited state (i.e., there is population inversion), it may be disturbed by the passage of a photon of frequency v 21, which corresponds to the energy gap Δ E of the transition from the excited state L2 to the ground state L1 (level 1). In this case, the excited atom relaxes to the ground state and is induced to produce a second photon having a frequency v 21. The original photon is not absorbed by an atom and the result is two photons of the same frequency. This process is called stimulated emission. In stimulated emission, the inductive photons have the same frequency and phase as the incident photons. In other words, the two photons are coherent. Thus, light amplification can be provided, as well as producing laser systems.

The process of magnon lasing (i.ya. korenblit and BG Tankhilevich, High frequency magnon generation by the magnetic resonance electrons and the stable of the magnon state, phys. lett. a,64,307(1977)) can be realized in ferromagnets with an exchange gap Δ in the electron spectrum, i.e. in ferromagnetic semiconductors and semimetals.

Fig. 3 illustrates a system 110 with magnonic lasing in half-metal. In one aspect, by emitting an acoustic magnon 114 (at about 10)^-12Time of seconds), the minority electrons 112 injected into the sub-band with spin-down 113 enter the high energy state 116 in the sub-band with spin-up 120, passing at the fermi level 118 (about 10) before reabsorbing the same magnons^-13Time in seconds) to relax the equilibrium electrons and lose energy rapidly. As a result, the electron strongly reduces its energy δ E120, which energy δ E120 is related to its relaxation on the electron with the fermi energy spin-up, and therefore cannot return to the spin-down subband by reabsorbing the magnon.

The number of unbalanced acoustic dipoles depends on the dipole-electronic damping ratio Γ_eDamping ratio gamma of and magnon-magnon_mAnd at a maximum "birth" rate Γ_eAnd a minimum death rate Γ_mThe time reaches a maximum value. This corresponds to the maximum number of unbalanced magnons. Frequency of lasingCorresponding to the minimum magnon wave vector

Because of the magnon-electronic damping ratio Γ_eAnd q is^-1Is in direct proportion; and magnon-magnon damping Γ_mAnd q is⁴Is proportional, therefore Γ_e/Γ_mAnd q is^-5Is in direct proportion. Multiple relaxations of the unbalanced magnons at the sample boundary occur before they scatter onto the balanced magnons. These boundary processes are insignificant, however, because they are elastic and do not change the energy of the magnons, whereas the momentum change in isotropic systems is not important. Thus, for a magnon laser, the minimum magnon wave vector

The lasing frequency is determined:

wherein D is the magnon stiffness.

Combining two magnons with frequency f and nearly equal antiparallel wave vectors in the directions (q/| q | and (-) q/| q |) produces a photon with frequency 2 f. This process is the reverse of the well-known process of parametric magnon generation by electromagnetic radiation. It is readily seen that the desired pair of dipoles always results from electron flow, with their momentum vectors oriented in (q/| q | and (-) q/| q |) directions, respectively. In fact, the fermi velocities of electrons in the current are randomly oriented in all directions because the drift velocity is very small compared to the fermi velocity. Thus, among the injected electrons, there are always two electrons with equal but antiparallel momentum. According to the law of conservation of energy and momentum, such electrons will generate two magnons with equal and antiparallel wave vectors, the angle between the vector (+) p/| p | and the vector q/| q |:

from this relationship it can be derived that for a magnon with | q | close to the moment of lasing q1, it is almost antiparallel to the vector p. At critical pumping current density j of 10⁴-10⁶A/cm²(the required critical pumping is in the same order of magnitude as that of a conventional semiconductor laser), the magnon lasing process begins and the device should generate high-power narrow-band terahertz radiation.

For example, estimate Co₂The lasing frequency of terahertz radiation in MnSi (001)/MgO heterostructures can provide stiffness

(according to Ritchie L. et al, Phys. Rev. B68, 104430) or

(according to Jan Thiene, Stanislav Chadov, Gerhard Fecher, Claudia Felser, Jurgen Kubler) J.Phys.D.: appl.phys.42(2009)084013)), an energy gap Δ ═ 0.6eV (Bjorn Hulsen and mathias Scheffler; phys. Rev Let.103,046802(2009)), and effective electron mass m_eff＝(1.15–1.67)m₀(Steffen Kaltenborn and Hans Christian Schneider, Phys. Rev B88, 045124 (23013.) terahertz can be twice as energetic as the minimum frequency of the unbalanced magnon (at the point of magnon lasing)

For the

For the

For the terahertz magnon laser 10 to operate efficiently at room temperature, it is first of all to have the largest possible polarization, so that the majority of the spin-up electrons in the spin-up sub-band are the only electrons present in the semimetal in the equilibrium state. Researchers at the University of Johannes Gutenberg (Johannes Gutenberg University of Mainz) directly observed 100% spin polarization of Heusler compound Co2MnSi (CMS) with a 985K high Curie temperature (Curie temperature) at room temperature.

In one aspect, the terahertz magnon laser 10 can be operated at room temperature by (a) injecting spin-down minority electrons into the upper subband of the semimetal, and (b) injecting a threshold critical minority electron current density into the upper subband to effect the start of the magnon lasing process.

In one embodiment of the present technology, FIG. 4 depicts the overall design of a voltage-based tunable terahertz magnon laser 140, which includes a spin injector 144, a tunnel junction 146, a ferromagnetic material 148, and a terahertz waveguide 150. In one embodiment, the terahertz waveguide can be implemented by using one or more 3D printing techniques. In one aspect, the ferromagnetic material 148 may comprise a magnon gain medium.

In one embodiment of the present technology, FIG. 5 illustrates a mechanism 200 for voltage-based continuous tuning of the magnon laser 140 of FIG. 4.

Generally, the voltage bias 210 is increased by going down 202 (having a Fermi level E) the spin_f1216) The increase of minority carriers in the sub-band of (a) results in an increase of minority current. In fact, the tunneling of the minority electron 220 with the largest energy through the tunnel junction 214 has the highest probability to propagate with spin-up 204 (with fermi level E) by flipping its spin_f2208) And produces a laser vector having the smallest possible magnon

Corresponding to the maximum energy epsilon_maxMomentum of the tunneled electrons.

Further increase of bias after reaching the lasing point leads to further increase of maximum energy and momentum of electrons with highest tunneling probability, thus leading to further reduction of magnon lasing vector and further corresponding reduction of terahertz frequency.

More particularly, theTuning in the system may be achieved by varying the bias voltage 210. In one embodiment, the voltage bias 210 may correspond to V_bias＝(Δ1+ε_p) Multiplied by dV. This will cause df to change the lasing frequency (tuning):

(df/f)＝-(dV/V)(Δ/ε_p)^1/2(equation 2)

Thus, the tuning of the lasing frequency is parametrically larger than the offset of the bias voltage, since a small change in bias will result in a large change in electron energy and thus in a large change in lasing frequency. Therefore, by using voltage-based tuning, it is possible to cover the entire terahertz frequency band at least in the (1-30) terahertz range.

For example, for Δ/ε_p≈10²(ii) a If dV/V ≈ 1 ≈ f>df/f is approximately equal to 10%, then f can be covered by changing the tuning voltage by only 1%_maxAnd 0.9f_maxThe thz frequency region in between.

In one embodiment, a micro-synchrotron may be provided on a chip. For example, the parameter is large (Δ/ε)_p)^1/2The frequency range (from the thz maximum to the thz minimum) and high output power make the thz magnon laser device effective as a micro-synchrotron on a chip, since a device of one chip size is needed to continuously cover a considerable lasing frequency range.

In one embodiment of the present technology, a method for tuning a frequency of terahertz radiation is provided. The method utilizes the apparatus of fig. 4, which in fig. 4 includes a spin injector 144, a tunnel junction 146 coupled to the spin injector, and a ferromagnetic material 148 coupled to the tunnel junction 146. The ferromagnetic material 148 includes a Magnon Gain Medium (MGM).

The method of tuning the frequency of terahertz radiation includes the step of applying a bias 142 to shift the fermi level of the spin injector 144 relative to the fermi level of the ferromagnetic material 148 to begin generation of unbalanced magnons by injecting minority electrons into the magnon gain medium of the ferromagnetic material 148.

The injected minority electrons enter a high-energy electronic state in the lower sub-band as the spins of the ferromagnetic material go up by flipping their spins during exchange. An unbalanced magnon is generated in this process. The resulting interaction between the unbalanced magnons results in the generation of terahertz electromagnetic radiation.

The method further comprises the step of tuning the frequency of the generated terahertz radiation by changing the value of the bias voltage 142.

FIG. 6 illustrates an example embodiment of a coherent terahertz magnon laser 600. It comprises at least one multilayer tunable microcolumn comprising (from bottom to top): (1) a substrate 602; (2) a bottom electrode 604; (3) a ferromagnetic material, further comprising a Magnon Gain Medium (MGM)606 coupled to the bottom electrode 604; (4) a tunnel junction 608 coupled to the magnon gain medium 606; (5) a spin injector 610 coupled to the tunnel junction 608; (6) a pinned layer 612 coupled to the spin injector 610; (7) a reference layer 614 coupled to the pinned layer 612; and/or (8) top electrode 616. The terahertz magnonic laser 600 further includes a receiving cavity 620 enclosing all the multilayer tunable microcolumns in one cavity. In addition, the terahertz magnon laser 600 may additionally or alternatively include a storage chamber 630.

As shown in fig. 6, in the exemplary embodiment including the accommodating chamber 620 but not including the storage chamber 630, the coherent characteristic is obtained by combining terahertz radiation generated by the unbalanced magnon due to the accommodating chamber 620.

In fact, the time to split a generated terahertz photon back into two unbalanced magnons is about 10^-7Seconds (same time as combining two nonequilibrium magnons into terahertz photons-see above).

On the other hand, the time for the terahertz photons to escape to free space is about

Τ_escape＝λ_THzC (speed of light) c/f_THz/c＝1/f_Thz.(ii) a (equation 3)

Thus, for example, for a photon with an energy of 10 terahertz, the escape time is about 10^-13Second (for photons with energy of 1 terahertz, the escape time is about 10)^-12Seconds) much less than 10^-7Second (time when the terahertz photons generated split back into two unbalanced magnonsM).

Thus, in certain embodiments, absorption of terahertz photons at the surface of the receiving cavity may be ignored (e.g., absorption may be minimized by coating the inner surface of the receiving cavity with gold) and initiation of an analog radiation process for the generated terahertz photons (e.g., based on Boson's Boson characteristics of photons) will result in the production of coherent photons that can be output through the outer aperture, d₁The size of (b) satisfies the flow condition:

λ_THz＜＜d₁＜＜L₁(ii) a (equation 4)

Wherein λ_THzIs the wavelength of the radiated terahertz radiation, L₁Is the size of the receiving cavity 620. Thus, the multilayer column represents a terahertz antenna, and the radiation surface of the multilayer column represents a terahertz gain medium.

However, in embodiments that include only the receiving cavity 620, the generation time of such coherent terahertz radiation is about 10^-7And second. This means that this terahertz radiation can only be modulated up to 10MHz (it can only be modulated after radiation generation). In one embodiment, the storage chamber 630 can have an L₂Dimension of (1) in L₁:L₂<L₁Is sized to enclose the receiving cavity 620.

Radiation penetrating from the receiving chamber 620 into the storage chamber 630 through the aperture D1 can be at any modulation frequency f less than the terahertz frequency generated_modulationAnd (3) modulation: f. of_THz:f_modulation<f_THz:

For practical purposes, if the radiation frequency is 10THz, the modulation frequency can be as high as 1 THz.

Radiation from the storage chamber 630 can be output through the outer orifice D2, the outer orifice D2 being sized to satisfy the flow condition: lambda [ alpha ]_THz＜＜D2＜＜L₂。

As shown in fig. 3, ferromagnetic materials may include a Magnon Gain Medium (MGM) in accordance with embodiments of the subject disclosure. The MGM comprises one conduction band divided into two sub-bands separated by an exchange gap, the first sub-band having a spin-up in the magnetization direction of the ferromagnetic material and the second sub-band having a spin-down opposite to the magnetization direction of the ferromagnetic material. The majority of electrons with spin-up are located in the first subband with spin-up.

As shown in fig. 7, when a bias voltage δ V is applied between the top electrode 616 and the bottom electrode 604, the at least one multilayer tunable microcolumn is configured to shift the fermi level of the spin injector 610 relative to the fermi level of the magnon gain medium 606 (e.g., relative to the fermi level of the ferromagnetic material comprising the magnon gain medium 606). After the fermi level of spin injector 610 is shifted relative to the fermi level of magnon gain medium 606, spin injector 610 injects minority electrons with spin-down into magnon gain medium 606 via tunnel junction 608 by tunneling, configured to generate unbalanced magnons in magnon gain medium 606, thereby generating terahertz radiation.

In one aspect, FIG. 3 may illustrate the physical characteristics of a magnon laser.

An unbalanced electron in the upper sub-band and spinning downward will rapidly emit a magnon with a large wave vector

Where m is the effective mass of the electron. According to the law of conservation of energy and momentum, if the energy e of the electron is measured from the spin down to the bottom of the subband_pMuch less than Δ, the wave vector q of the transmitting magnon lies in the interval q₁≤q≤q₂Wherein

p₀＝(2mΔ)^1/2,p＝(2mε_p)^1/2＜＜p₀. The frequencies of these magnons are located in the terahertz region.

Rate of generation of magnon

And

their relaxation (upon collision with a balanced magnon) is the wave vector

As a function of (c). Thus, the unbalanced magnon distribution function

At a certain wave vector

Has a maximum value.

Increasing with increasing electron pumps and as a function of simulating the emission of the magnon

In that

Approach to

And is growing fastest. When the pump reaches a certain critical value,

starts to increase very quickly with the increase in electronic pumps. Under certain conditions, has

The generation of the magnons becomes like an avalanche and the magnon system becomes unstable. See the reference for details: ya, Korenblit and B.G.Tankhilevich, Sov.Phys. -JETP,46,1167 (1977); i.ya.korenblit and b.g.tankhilevich, sov.phys. -JETP lett.24,555 (1976); i.ya.korenblit and b.g.tankhilevich, phys.lett.a 64,307(1977) and the following equations. As a result, intense terahertz radiation can be obtained.

In one aspect, the generation of the magnons may be provided based on a system of equations.

System of equations for controlling electronic behavior

And a magnetic vibrator

The distribution function is obtained in the following paper: i.ya.korenblit and b.g.tankhilevich, sov.phys. -JETP,46,1167(1977) in the case of ferromagnetic semiconductors (in the case of semimetals we have very similar basic equations).

They are in a stable state of

(equation 5)

Fig. 8 and 9 illustrate these equations in a generally non-stationary case.

Here, the

Is the relaxation rate of the magnon in collision with the electron

Wherein v is₀Is the unit cell volume.

γ_emIs electron-magnon relaxation rate:

the delta function delta (y | epsilon) of the "smeared" takes into account the finite lifetime of the electrons in the final state, caused by the interaction with the photo-phonon, which may be strong in ferromagnetic semiconductors and has an important ionic contribution to the chemical bond. In one aspect,

due to the emission of longitudinal phonons in the case of ferromagnetic semiconductors (or scattering on equilibrium electrons with fermi energy in the case of semimetals), this rate γ_↑(p，ε_p) Is a known electronic damping rate. For energy ε_pElectrons near Δ, the rate being estimated as

γ₈(ε_p)＝(π/2)αΩ(Ω/Δ)^1/2ln (4 Δ/Ω) < Δ (equation 9)

Where Ω is the energy of the photo-phonon and α is the intensity of the electron-phonon interaction.

The function g (ε) is the electron generation function, spin down. We consider it as a delta function

g(ε_p)＝g₀εδ(ε-ε_p) (equation 10)

We assume that the following energy ε is small, ε < Δ.

The second term of l.h.s. in the first part of equation 5 describes the relaxation of the unbalanced magnon upon collision with the balanced magnon, assuming that

Close to the value of the equilibrium thereof,

is the magnon-magnon relaxation rate. From equation 5, the following can be derived

The integral of (a) is calculated,

wherein

And

equation 12 formally reminds the expression of the magnon distribution function under parametric pumping conditions. With the difference that here the rate r is_eIs itself

Because the number of emitted magnons depends on the distribution function f of the spin-down electrons_↓According to equations 6 and 7, it is not only determined by the pump g (. epsilon.)_p) The decision is also determined by some mean value over the magnon distribution function (equation 14). Therefore, the temperature of the molten metal is controlled,

is not the same as the case of parametric pumping.

In one embodiment of the present invention,

may be associated with a strong pump.

In another embodiment, the resulting unbalanced magnon is isotropic.

In certain embodiments, the magnons and the electron spectrum are isotropic. Then Γ_e(q) and Γ_m(q) is not dependent on

In the direction of (a).

The relaxation rate Γ (q) is generally a power function of q and can be written as

More specifically if Γ_m(q) is determined by magnon-magnon exchange scattering, then for magnon, t is 4, energy

Greater than kT, and

for a magnon, t is 3, energy

Less than kT.

When g is₀Exceeds a critical value G_cAt that time, the strong pumping rule (strongpumping region) starts to work. If the phonon damping of the electrons is less than (ε Δ)^1/2Then the threshold is estimated as

G_c＝2g_c/(t+1),

g_c＝(Δ/ε)^3/2Γ_m(q₀)[1+N⁽⁰⁾(q₀)](equation 16)

In g₀>G_cThe function N (q) increases exponentially with pumping

N(q)＝[1+N⁽⁰⁾(q₀)](p₀/2p_ε(t+1))exp(g₀/G_c) (equation 17)

If q falls within the smooth region

N (q) with wave vectors outside the above range does not depend on the pump.

Thus, under sufficiently strong pumping, the magnon distribution function is at

There is a peak.

In one embodiment, the number of electrons pumped per unit cell per second, β, can be defined as:

pumping estimation by equation (10)

In g₀＝G_cIn the case of critical pumping beta_cIs that

β_c＝(v₀ q³ ₀/(2(t+1)π²))Γ_m(q₀)[1+N⁽⁰⁾(q₀)](equation 21)

In embodiments where high frequency dipoles are required, their relaxation is mainly due to the four-dipole exchange interaction. Γ published in the following references (v.g. vaks, a.i. larkin and s.a. pikin, JETP 53(1967)) was used_mExpression, T/T can be estimated_C0.2, and

N⁽⁰⁾(q₀)＜＜1:Γ_m.10⁸–10⁹sec^-1。

therefore, estimate β from (equation 21)_c.10⁵–10⁷sec^-1N can be determined⁽⁰⁾(q₀) Are small.

To understand these estimates, consider a model in which the spin-down potential is orientedThe seed is emitted to 1cm²In the active area of the surface area. The lattice constant a of EuO is about 5x10^-8cm, i.e. the unit cell volume is about v₀.10^-22cm³. Critical value N_e.β_c x v₀.10²⁸-10²⁹cm^-3sec^-1. This is the number of electrons that should cross the edge to reach 1cm in a second³A critical number of magnons to be emitted within the volume. However, electrons will emit magnons very close to the edge, which can be estimated in the following way.

Electron-magnon frequency gamma_emIs 3x10¹²-10¹³sec^-1. Energy of 10^-2Electrons of the order of magnitude Δ have a velocity of 5x10⁶-10⁷cm x sec^-1. This gives the mean free path (mean free path) of electrons with respect to the emission of the magnons as: l.10^-6cm. Thus, all electrons entering the sample (including the magnon gain medium) through the selected side will emit a magnon at that distance from that side. Therefore, only the region of width l is active, and we obtain a current density j ═ N_ex l electrons/sec x cm². The charge of one electron is 1.6x10^-19And Q. Considering 1 x Q/sec-1A, we finally get: j-10⁴-10⁵A/cm². Easily up to 10 in semiconductors (or semi-metals)⁵-10⁶A/cm²The current density of (1). Under the pulse regime, up to: j-10⁹Current density j of A/cm.

Critical pumping G_cThe physical meaning of (a) can be understood as follows. Ratio Γ of the rate of formation of a magnon to its relaxation rate_e/Γ_mIn that

Reaches a maximum value and is at

The minimum value is reached, i.e. there is redundant generation at the left end of the interval compared to the right end. Stimulated emission results in an increase in this asymmetry. If N is present⁽⁰⁾>1, nonlinear generation starts when the difference between the number of unbalanced dipoles at the end of the generation interval is equal to the number of balanced dipoles. On the other hand, if the inequality (N) is reversed⁽⁰⁾<1) If this is true, then the nonlinear generation starts when the difference between the number of unbalanced magnons at the end of the generation interval is equal to 1.

If the electronic damping caused by photoacoustic photon scattering is large,

critical pumping G'_cLess than gc estimated by (equation 16)

G’_c＝πg_cγ_↑[ Delta ] (equation 22)

Function of critical section N (q) with g₀ ²Is increased, the wave vector interval of the generated magnon is reduced to 1/g₀：

N(q)＝[1+N⁽⁰⁾(q)](g₀/GΝ_c)²(equation 23)

It should be emphasized that only the main generation rules are considered here. More details can be found in the following references: ya, Korenblit and B.G.Tankhilevich, Sov.Phys. -JETP,46,1167 (1977).

In one embodiment, the effect of anisotropy and/or instability of the magnetic vibrator system may be determined.

If the rate of production

And relaxation rate

Is dependent on the wave vector

Then in a non-linear rule the stimulated emission of the magnons results in a strong anisotropy of the magnon distribution function. For example, one can consider the anisotropy due to the magnon spectrum

The anisotropy of (2). q is close to

The spectrum of the magnon can be written as

ω_q＝Dq²(1+Λsin²θ), (equation 24)

Wherein

Λ＝2πgΦ_B M_s/ω_p0< 1, (equation 25)

M_sIt is the intensity of the magnetization that is,

is a vector

And

the angle therebetween. If inequality

Is established, then

The anisotropy of (a) means that the generation is maximum at a certain angle theta.

Taking this into account, when the damping is greater, i.e.

Since the anisotropy is small (Λ < 1), the anisotropy is only effective with a sufficiently strong pumping action, greater than the critical pumping, equation (18). At G estimated by this equation_cThe number of magnons starts to increase as in the case of isotropy. If it is assumed that the fundamental equation (equation) for near-equilibrium magnon generation is described5) Also effective above the critical pumping, the effect of small anisotropy can be revealed.

As shown in the following references: ya, Korenblit and B.G.Tankhilevich, Sov.Phys. -JETP,46,1167(1977), with maximum production occurring at θ near zero and q near p₀On the magnetic vibrator. If the pumping reaches a critical value g^*

Function(s)

Become into

Wherein

We are in

At, i.e. in ∈_qAt Δ, get

When θ is 0, the denominator of the expression becomes zero. A stable solution of equation (1) exists only below g^*The pumping level of (a). When the pumping level reaches a critical value g^*The number of magnons will increase avalanche, while the wave vector of these non-equilibrium anisotropic magnons points in the direction of magnetization and equals p₀。

Note that at sufficiently low temperatures, three-dipole scattering may be more important than the four-dipole exchange scattering discussed above. However, in contrast to the four-magnon exchange scattering probability, the three-magnon scattering probability is highIs highly anisotropic and is in²θcos²Theta is proportional. If this is the case, instability of the magnons with 0 and pi/2 should be expected.

In one embodiment, terahertz radiation can be generated.

The interaction of the magnons with electromagnetic radiation is considered in the following references: kaganov and V.M.Tsuker, Sov.Phys. -JETP 37,587 (1960). Combining two vectors having wave vectors q and q^’The magnon generates a photon having a wave vector

And a frequency v_kIs equal to

ω_q+ω_q'＝ν_kCk, (equation 30)

Where c is the speed of light.

According to these conservation laws k is much smaller than q, i.e.

Results using the same reference: m.i.kaganov and v.m.tsukernik, sov.phys. -JETP 37,587(1960), the rate of change of the photon distribution function n (v) can be derived by:

therein, the

Where Φ is the Bohr magneton. The last term in (equation 62) describes the relaxation of the generated photons, whereas τ_phIs the photon relaxation time.

For EuO, at q₀＝2.6x10cm^-1、

And 4 π M_S＝24x10³In the case of Gs, W.2x10 can be obtained⁷sec^-1。

If the magnon distribution function is isotropic, then it can be integrated in (equation 31) to get the following equation:

by analyzing this equation, it is clear that in the initial stages of production, when N is less than N, the number of photons will follow N as long as the photon relaxation is small enough²And (4) increasing. As n increases, the negative term in (equation 33) becomes significant and the photon reaches a steady state where dn/dt is 0. If this is the case, we have the following expression for the number of photons n in the steady state:

wherein W is 16W/15.

If w τ_phVery large, w τ_ph> 1/N, the number of photons is as follows:

on the other hand, if 1/N²＜＜wτ_phIf < 1/N, the number of photons is as follows:

n＝wτ_phN²1n N (equation 36)

Finally, if the relaxation of the photon is very fast, w τ_phN²If < 1, the pumping efficiency is low, and

n≈n⁽⁰⁾(equation 37)

In one embodiment, Co may be estimated₂In MnSi (001)/MgO heterostructureThe frequency of the terahertz radiation.

In an aspect, a correlation parameter may be estimated.

For example, stiffness can be estimated from ritchai l.et al, phys.rev.b 68,104430

Or according to Jan Thiene, Stanislav Chadov, Gerhard Fecher, Claudia Felser, Jurgen Kubler) J.Phys.D.: appl.Phys.42(2009)084013)

In another embodiment, the material may be prepared according to Bjorn Hulsen and Matthias Scheffler; phys. rev let.103,046802(2009) determines the energy gap, for example Δ ═ 0.6 eV.

In yet another embodiment, the compound may be prepared according to Steffen Kaltenborn and Hans Christian Schneider, Phys. Rev B88, 045124 (23013); estimate the effective electron mass m.Y. Smith, B.Segal, Phys.Rev.B 34,5191(1986)_eff＝(1.15–

1.67)m₀. Thus, the frequency for terahertz radiation is twice the minimum frequency of the spin wave (at the point of magnon excitation)

For the

(5.5²-6.2²)10¹⁴cm^-2＝2x466(30.25-38.44)

For the

F＝(13.10-20.24)THz

In one embodiment, the time to generate such coherent terahertz radiation may be about 10^-7And second. This means that such terahertz radiation can only be modulated at most 10MHz (for example, only after the radiation has been generated). This restriction may be achieved by introducing a storage chamber 630 of size L2 enclosing a storage chamber of size L1: L₂<L₁And the receiving cavity 620.

In one aspect, radiation penetrating from the containment chamber 620 into the storage chamber 630 via the aperture D1 may be at a frequency f less than the terahertz frequency generated_THzAny modulation frequency f_modulationCarrying out the modulation of_modulation<f_THz。

For practical purposes, if the radiation frequency is 10THz, the modulation frequency can be as high as 1 THz.

Radiation from the storage chamber 630 can be output through an outer orifice D2 sized to satisfy the flow conditions:

λ_THz< D2 < L2. (equation 38)

Specific materials may be employed for the different layers. In one embodiment, the substrate 602 may include: alumina (Al)₂O₃) Indium tin oxide (InTnO); silicon (Si); silicon on sapphire (SoS); or magnesium oxide (MgO).

In another embodiment, the bottom electrode 604 may include: cobalt iron alloy (Co)_0.5 Fe _0.5) (ii) a Silver (Ag); gold (Au); platinum (Pt); cobalt (Co); palladium (Pd); titanium (Ti); or titanium Tungsten (TiW).

In another embodiment, the magnon gain medium 606 may comprise chromium dioxide (CrO)₂) (ii) a Half-metal ferromagnetic oxide Sr₂FeMoO₆(ii) a Heusler alloy Co₂MnGe; heusler alloy Co₂Mnsi (cms); heusler alloy Co₂Fesi (cfs); heusler alloy Co₂Mnsn (cms); or heusler alloy Co₂FeAl_0.5Si_0.5(CFAS)。

For example, Co₂MnSi can be used to realize magnetismThe material of the oscillator gain medium 606. In fact, in a recent paper published in Nat commun, 5 months and 30 days 2014; m. Jourdan et al, "Direct adherence of half-compatibility in the Heusler compound Co2 MnSi", Co₂The MnSi samples were prepared in a synchrotron ultraviolet photoelectron spectroscopy (SRUPS) chamber consisting of a sputtering chamber, a Molecular Beam Epitaxy (MBE) chamber, and a helium discharge lamp (21.2 eV) equipped and a hemispherical energy analyzer (energy resolution) with a multichannel spin filter

Sielman function S ═ 0.42 ± 0.05) in an ultra-high vacuum cluster. First, an epitaxial buffer layer of heusler compound Co2MnGa (30nm) was grown on a MgO (100) substrate by Radio Frequency (RF) sputtering at room temperature. By an optimized additional annealing process, an L21 sequence was obtained at 550 ℃, as shown by high energy electron diffraction (RHEED) and X-ray diffraction (XRD). Co2MnSi (70nm) was radio frequency sputtered on top at room temperature. Under the induction of the buffer layer, the Co2MnSi film already shows a certain degree of L2 when being deposited₁Surface sequence. The sequence was improved by additional annealing as evidenced by RHEED on the surface of the film.

In another example, a material that may be used for the magnon gain medium 606 may be L2₁Co2+ x Fe1-x Si heusler alloys of the phases. Please refer to "Co Fe Si/MgO (001) Heusler alloys: fluorescence of off-stoichiometrics and late degradation on the magnetic properties in bulk and on MgO (001)", published in applied physical journal 109,07E128 (2011); written by h.c.herper et al.

In another embodiment, tunnel junction 608 may include magnesium oxide (MgO); alumina (Al)₂O₃) (ii) a Or spinel MgAl₂O₄。

In the paper "MgAl O (001) based magnetic tunnel junction maps by direct sputtering of a sintered target of a sintered MgAl O spinel" published by Mohamed Belmouraik, Hiroaki Sukegawa, Tadakatsu Ohkubo, Seiji Mitani and Kazuhiro Hono in Appl. Phys.Lett.108,132404(2016), a manufacturing process of epitaxial MgAl O for Magnetic Tunnel Junctions (MTJ) was developed by using the direct sputtering method from a sintered target of MgAl O spinel.

Annealing a sputter-deposited MgAl O layer sandwiched between Fe electrodes results in the formation of a (001) -oriented, cation-disordered spinel with an atomically sharp interface and lattice-matched to the Fe electrodes. A large tunnel magnetoresistance ratio of up to 245% at 297K (436% at 3K) and excellent bias voltage dependence were achieved in the Fe/MgAl O/Fe (001) MTJ. These results indicate that direct sputtering is an alternative approach to achieving high performance MTJs with spinel based tunnel barriers.

Spin injector 610 may be selected from the group consisting of: chromium dioxide (CrO)₂) (ii) a Half-metal ferromagnetic oxide Sr₂FeMoO₆(ii) a Heusler alloy Co₂MnGe; heusler alloy Co₂Mnsi (cms); heusler alloy Co₂Fesi (cfs); heusler alloy Co₂MnSn; and heusler alloy Co₂FeAl_0.5Si_0.5(CFAS)。

For example, the paper "Structural and magnetic properties and channel magnetic properties for Co 5 published in Journal of Physics D: Applied Physics, Volume 39, Number 5 by K Inomata et al₂(Cr,Fe)Al and Co₂In FeSi full-Heusler alloys ", Co was studied₂(Cr_1-xFex) Al (x is more than or equal to 0 and less than or equal to 1) and Co₂Structure and magnetization of FeSi perhheusler alloys. Film deposition on thermally oxidized Si (SiO) by ultra-high vacuum sputtering at various temperatures₂) And an MgO (001) single crystal substrate. After deposition at Room Temperature (RT), the film was also post annealed. By using Co₂YZ (20nm)/Al (1.2nm) -oxide/Co₇₅Fe₂₅(3nm)/IrMn (15nm)/Ta (60nm) Stack Structure A magnetic tunnel junction with a Perheusler alloy electrode was fabricated and the pair 10 was etched using electron beam lithography and Ar ion²μm²The junction area is micro-machined, wherein Co₂YZ stands for Co₂(Cr_1-xFex) Al or Co₂FeSi. The tunnel barrier is formed by depositing 1.2nm of aluminum followed by plasma oxidation in the chamber. x-ray diffraction revealed A2 orB2 structure depending on the heat treatment conditions and substrate, but not Co₂(Cr_1-L2 of xFex) Al (x is more than or equal to 0 and less than or equal to 1) film₁And (5) structure. However, when Co is used₂When an FeSi thin film is deposited on an MgO (001) substrate at a high temperature of more than 473K, L2 is obtained₁And (5) structure. For using Co₂(Cr_0.4Fe_0.6) The junction of the Al electrode has a maximum Tunnel Magnetoresistance (TMR) of 52% at Room Temperature (RT) and 83% at 5K. Although using a circuit having L2₁Co of structure₂The junction of the FeSi electrode showed 41% TMR at RT and 60% at 5K, but this could be improved by using a buffer layer to reduce Co₂Lattice mismatch between FeSi and MgO (001) substrates.

The pinning layer 612 may be selected from the group consisting of: iridium manganese chromium (IrMnCr); iridium manganese (IrMn); nickel manganese (NiMn); nickel manganese chromium (NiMnCr); nickel manganese iron (NiMnFe); nickel manganese iridium (NiMnIr); nickel manganese palladium (NiMnPd); nickel manganese platinum (NiMnPt); nickel manganese rhodium (NiMnRh); platinum manganese (PtMn) and nickel manganese ruthenium (NiMnRu).

In one embodiment, the pinning layer 612 may also include a Ruderman-Kittel-Kasuya-Yosida nonmagnetic pinning layer.

For example, as shown in FIG. 2, the RKKY interaction exhibits opposite ferromagnetic polarity for a ruthenium spacer having a layer thickness of about 8 angstroms. (see above).

In another example of a spacer that utilizes RKKY interaction and exhibits opposite ferromagnetic polarity, is a Cu spacer. In one embodiment, the Cu Spacer may correspond to the Cu Spacer described in IEEE Transactions on Magnetics, Volume:43 Issue:2 "Current-in-Plane Giant magnetic Sensor Using a Thin Cu Spacer and Dual Nano-Oxide Layers With a DR Greater mean 20 Ohms/sq, published by Michael A.Seigler et al.

The reference layer 614 may comprise a ferromagnetic material that is used to select the orientation of the magnon gain medium 606 in a certain direction.

The reference layer 614 may be, for example, a free layer. The reference layer 614 may be implemented using CFA (B2-ordered Co2 FeAl).

For example, the reference layer 614 may correspond to the reference layers described by Hiroaki Sukegawa, Zhenchao Wen, Kouta Kondou, Shinya Kasai, Seiji Mitani, and Koichiro Inomata, Applied Physics Letters 100,182403 (2012); "Spin-transfer switching in full-Heusler Co2FeAl-based magnetic tunnel junctions".

In another example, the reference layer 614 can be a perpendicularly magnetized [ Co/Pd ] based reference layer and an in-plane magnetized CoFeB sense layer with various thicknesses (tCoFeB). A linear TMR curve of the out-of-plane magnetic field was successfully obtained, with a dynamic range exceeding 600Oe, corresponding to the coercivity of the [ Co/Pd ] based reference layer. MTJ shows a maximum sensitivity of 0.026%/Oe for tCoFeB 1.8nm, and a minimum nonlinearity at t 3nm, 0.11% full scale. The sensitivity and nonlinearity of the MTJ is significantly related to t due to the change in the anisotropy field of the CoFeB sensing layer. Please refer to "Magnetic Tunnel Junctions With [ Co/Pd ] -Based Reference Layer and CoFeB Sensing Layer for Magnetic Sensor" published by Takafumi Nakano et al in IEEE Transactions on Magnetics (Vol.52, No. 7, 2016, 7 months).

The top electrode 616 may be selected from the group consisting of: cobalt iron alloy (Co)_0.5 Fe _0.5) (ii) a Silver (Ag); gold (Au); platinum (Pt); cobalt (Co); palladium (Pd); titanium (Ti); and titanium Tungsten (TiW). Each of these materials can be deposited by MBE or sputtering.

Thus, the terahertz magnon laser 600 generates terahertz radiation based on the magnon laser effect. For reference, see U.S. patent nos.: 7,430,074, respectively; 7,508,578, respectively; 9,136,665. In one embodiment, the frequency of the generated coherent terahertz radiation can be tuned by changing the bias voltage 618. In another embodiment, the receiving cavity 620 may be employed to output tunable coherent terahertz radiation into the storage cavity 630. Additionally or alternatively, the storage chamber 630 may employ output tunable coherent terahertz radiation. The tunable coherent terahertz radiation can be modulated by modulating the bias voltage 618 with a modulation frequency. In another embodiment, the tunable coherent terahertz radiation can be modulated by modulating the output coherent radiation by external means. In another embodiment, the tunable coherent terahertz radiation can be modulated by modulating the output coherent radiation using a piezoelectric material to mechanically change the size of aperture D1 and/or outer aperture D2. In yet another embodiment, the tunable coherent terahertz radiation can be modulated by modulating the output coherent radiation using a synthetic ceramic material. Aperture D1 and/or outer aperture D2 may output coherent terahertz radiation.

In one embodiment, a coherent terahertz magnon laser may be provided for communication applications. The small divergence of the coherent terahertz laser beam can allow for a large increase in received power.

The spot size wz of the coherent laser beam is a function of the position along the gaussian beam propagation direction z and depends on the aperture size d and the wavelength λ of the transmitting antenna. Coherent terahertz laser beam dimension w at distance z 0 from aperture wo d_zEstimated by A.E. Siegman, Lasers (University Science Books 1986)

w_z＝w_o√1+(λz/πw_o ²)²(equation 39)

Fig. 10 illustrates a device 1000 in accordance with one or more embodiments described herein. The device 1000 may include a magnon laser chip 1002 having a cavity 1020. The chamber 1020 may include a window 1024 that may be an aperture of the chamber 1020. In certain embodiments, the cavity 1020 may include a height L3. As shown in fig. 10, from dimension w_oA window 1024 of 1mm (d) emits light having λ (10THz) 3x10^-2mm and the size of the coherent terahertz beam at a distance z of 100m is: w is a_z＝10^-3m√1+(3 10^-5m 10²m/3.14 10^-6m²)²＝1m。

On the other hand, the divergence of an incoherent terahertz beam at a distance of 100m will include a spherical surface with a radius of 100 m. Thus, by using coherent beams, the link budget is increased by 40 dB. In fact (R)²/w_z ²)＝100²/1²＝10⁴40 dB. Thus, the receiver may use a small antenna to receive such signals. Thus, a secret recipient can receive a terahertz laser beam spot of size 1m at a distance from the transmitter 100m at an undetectable terahertz frequencyShort-term secret communication. This task can be simplified by transmitting several such coherent laser beams simultaneously.

In one embodiment, the cavity 1020 may be a highly reflective cavity. The cavity 1020 may be made of, for example, Silicon film (see, for example, "High-efficiency terrestrial-wave generation in Silicon membrane waveguides"; conference-Proceedings-of-SPIE/9199.toc)91990D (2014) activities published in Proceedings Volume 9199, Terahertz emerters, Receivers, and Applications V: SPIE optical Engineering + Applications (/ conference-proceedings-of-SPIE/brown/SPIE-Optics-Photonics/SPIE-optical-Engineering Applications/2014),2014, san Diego, Calif., USA, published by Hongjun Liu et al.

In another embodiment, the window 1024 may be a high terahertz and far infrared transparent window (e.g., aperture) made of Ge-Ga-Te far infrared chalcogenide glass, similar to the Ge-Ga-Te far infrared chalcogenide glass described in "Novel NaI enhanced Ge-Ga-Te far-infrared-associated chalcogenoide glasses", published in infrared physics and technology; ci Cheng et al, vol 72, 9/2015, page 148-152.

As shown in fig. 10, the size of the coherent terahertz beam emitted from the window 1024 is: dimension wo-d-1 mm, λ (10THz) 3x10^-2mm, at a distance z of 100m will be: w is a_z＝10^-3m√1+(3 10^-5m 10²m/3.14 10^-6m²)²＝1m。

On the other hand, the divergence of an incoherent terahertz beam at a distance of 100m will include a spherical surface with a radius of 100 m. Thus, by using coherent beams, the link budget may be 40dB better. In fact (R)²/w_z ²)＝100²/1²＝10⁴40 dB. Thus, the receiver may use a small antenna to receive such signals. Thus, the secret receiver can receive short-term secret communications on an undetectable terahertz frequency by detecting a terahertz laser beam spot of 1m size at a distance from the transmitter 100 m. This task can be simplified by transmitting several such coherent laser beams simultaneously. Example (b)For example, coherent laser beam 1004, coherent laser beam 1006, and coherent laser beam 1008 can be transmitted simultaneously.

In one embodiment, the cavity 1020 may be made of Silicon film (see "High-efficiency Terahertz-wave generation in Silicon membrane waveguides"; conference-Proceedings-of-SPIE/9199.toc, published in Proceedings Volume 9199, Terahertz emerters, Receivers, and Applications V) 91990D (2014).

Moving: SPIE Optical Engineering + Applications (/ conference-proceedings-of-SPIE/brown/SPIE-Optics-Photonics/SPIE-Optical-Engineering Applications/2014, san Diego, Calif., USA, published by Hongjun Liu et al.

In one embodiment, window 1024 may be made of Ge-Ga-Te far infrared chalcogenide glass (see "Novel NaI improved Ge-Ga-Te far-infrared chalcogenide glasses", published in Infrared physics and technology; Vol. 72, 9/2015, p. 148-152 by Ci Cheng et al).

In one embodiment of the present technology, fig. 11 is a front view of a terahertz generator that includes a plurality of single terahertz magnon lasers, each such single terahertz magnon laser further including a single multilayer column {26, 1; 26, 2; 26, i; .., 26, k }; where i and k are integers. Each such single multi-layer pillar 26, i is coupled to the bottom electrode 14, wherein the bottom electrode 14 is coupled to the substrate 12.

In one embodiment of the present technology, FIG. 12 shows a terahertz magnon laser including a plurality of single terahertz magnon lasers 10, 1; 10,2 … 10, i, … 10, k; front view of the terahertz generator of (1), i and k are integers; each such single terahertz magnon laser also includes a single multilayer column 80, a bottom electrode 14, a substrate 12, and a terahertz transparent medium 60 separating at least two such single multilayer columns. A bias voltage (not shown) applied across each single terahertz magnon laser 10, i from the top to the bottom electrode 14 of the single multilayer pillar 80 is configured to inject the spin current of the spin injector 610 into the magnon gain medium 606. The injected current enables the spin-down electrons of the spin injector 610 to transition through the tunnel junction 608 into the sub-band with the magnon gain medium 606 spin-down, triggering the magnon lasing process by entering the sub-band with the magnon gain medium 606 spin-up, which results in the generation of terahertz radiation emitted from the top surface 45 (of FIG. 13) of the device. For reference, see U.S. patent nos.: 7,430,074, respectively; 7,508,578, respectively; 9,136,665.

In one embodiment of the present technology, still referring to fig. 12, the distance L between any two adjacent multilayer pillars (e.g., the distance 62 between two adjacent multilayer pillars 26,1 and 26, 2) may be greater than the wavelength λ of the emitted terahertz signal_THzSuch that each generated terahertz photon can be born outside the magnon gain medium region.

D>λ_THz(equation 40)

In one embodiment of the present technology, referring to fig. 12, the terahertz transparent medium 60 is selected from the group consisting of: a crystal terahertz transparent material; and polymer terahertz transparent materials.

In one embodiment of the present technology, referring to fig. 12, the terahertz transparent medium 60 is selected from the group consisting of the following crystal materials: high resistance Float band Silicon (High resistance Float Zone Silicon; HRTZ-Si); crystal quartz; and sapphire.

Crystals such as silicon, crystal quartz, and sapphire are very important for the production of terahertz optical devices. For reference, see x. — c.zhang, j.xu, brief introduction to terahertz wave photonics, Springer Science + Business Media, LLC 2010.

Apart from synthetic diamond, high resistivity silicon is the only isotropic crystalline material suitable for a very wide range of waves, from NIR (1.2 μm) to millimetre (1000 μm). It is less costly to grow and process than diamond. Furthermore, it may have considerable dimensions, allowing the fabrication of rapidly developing terahertz electronic components on this basis.

One of the best materials with wavelengths over 50 μm is z-cut crystalline quartz. It is important that the z-cut crystal quartz window be transparent in the visible range, thus allowing easy tuning using a HeNe laser, without changing the light polarization state, and can be cooled below the lambda point of liquid helium. Crystalline quartz is a birefringent material and care should be taken if the polarization of the radiation is important.

Sapphire is transparent in both the terahertz region and the visible region, as is crystalline quartz. For measurement samples with a thickness of 1 to 5mm, the transmission below 600 μm depends to a large extent on the sample thickness. Sapphire can also be used to fabricate terahertz light guide antennas, as with HRFZ-Silicon, because of the similar refractive index values of terahertz.

In one embodiment of the present technology, referring to fig. 12, the terahertz transparent medium 60 is selected from the group consisting of the following polymer materials: high Density Polyethylene (HDPE); polymethylpentene (TPX); polyethylene (PE); and Polytetrafluoroethylene (PTFE).

Among the wide variety of available polymers, there are some excellent terahertz transparent materials with relatively low reflectivity. In this sense, the best materials are TPX (polymethylpentene), Polyethylene (PE), polypropylene (PP) and polytetrafluoroethylene (PTFE or Teflon). At longer wavelengths, the structure of transmission of these polymers is less and flat. Into shorter wavelengths, mainly below 200 μm, characteristic bands of natural vibration occur and scattering increases due to non-uniformity. Polymers typically become increasingly opaque at shorter wavelengths.

Polymethylpentene (TPX) is the lightest of all known polymers. It is optically transparent in the ultraviolet, visible and terahertz ranges, allowing, for example, the use of a HeNe laser beam for alignment. The refractive index is about 1.46, relatively independent of wavelength. The losses are very low, down to millimeter wavelengths. TPX has excellent heat resistance and is highly resistant to most organic and inorganic commercial chemicals. TPX is a rigid, solid material that can be mechanically molded into various optical components, such as lenses and windows. In addition, TPX is used especially for CO₂The laser pump molecular laser acts as an output window because it is transparent throughout the terahertz range and completely suppresses about 10 μm of pump radiation. In addition, the TPX window serves as a "cold" window in the cryostat. The terahertz transparency of TPX does not change with temperature. Temperature coefficient of refractive index of 3.0 x10^-4K^-1(range of 8-120K). And is used inTPX shows excellent optical performance compared to other materials operating in the hertz range, and can for example well replace picarin (tsuruppica) lenses. Furthermore, TPX is cheaper and commercially available than Picarin.

Polyethylene (PE) is a crystalline material that is light elastic. Depending on the grade, it can be heated to 110 ℃ and cooled to-45 ÷ -120 ℃. PE has good dielectric properties, chemical resistance and radiation resistance. Instead, it is unstable to ultraviolet radiation, fats and oils. PE is biologically inert and easy to process. The density (23 ℃) is 0.91-0.925g/cm 3. The tensile flow limit (23 ℃) is 8-13 MPa. The elastic modulus (23 ℃) was 118-350 MPa. The refractive index is about 1.54 and is fairly equal over a broad wavelength range. High Density Polyethylene (HDPE) is commonly used for the production of components. In addition to the rather thick lenses and windows, terahertz polarizers also use thin HDPE films. In addition, HDPE is used as the window for the Golay cell. Terahertz transmission of HDPE is independent of the temperature that allows the use of HDPE windows in cryostats. Temperature coefficient of refractive index of 6.2 x10^-4K^-1(range of 8-120K).

Polytetrafluoroethylene (PTFE) is a white solid at ambient temperature and has a density of about 2.2g/cm 3. Its melting point is 327 ℃, but its properties are maintained at useful levels over a wide temperature range of-73 ℃ to 204 ℃. The refractive index is about 1.43 over a broad wavelength range.

In one embodiment of the present technology, FIG. 13 shows a top view of a terahertz generator comprising a plurality of single terahertz magnon lasers, each such single terahertz magnon laser comprising a single multilayer pillar 80, and a terahertz transparent medium 60 filled between such single multilayer pillars 80.

In one embodiment of the present technology, at least one single terahertz magnon laser 10, i (fig. 12) generates terahertz radiation based on the magnon lasing effect. For reference, see U.S. patent nos.: 7,430,074, respectively; 7,508,578, respectively; 9,136,665.

In one embodiment of the present technology, a method of generating terahertz signals is provided by using the apparatus 25 of FIG. 11, which includes a plurality of terahertz magnon laser generators (10, 1-10, k) and a terahertz transparent medium (60 of FIG. 12) separating at least two such terahertz magnon laser generators. At least one such terahertz magnon laser generator 15 of fig. 1 comprises: a substrate 12; a bottom electrode 14 coupled to the substrate 12; and a multilayer pillar 26 coupled to the bottom electrode 14. The multilayer pillar further includes a bottom layer 16, the bottom layer 16 further including a magnon gain medium; a tunnel junction 18 coupled to the bottom layer 16; a spin injector 20 coupled to the tunnel junction 18; a pinned layer 22 coupled to the spin injector 20; and a top electrode 28 coupled to the pinned layer 22. In one embodiment, the spin injector 20 may be a top layer comprising a spin injector.

In one embodiment of the present technology, the method of generating a terahertz signal by using the apparatus 25 of fig. 11 further comprises: (A) fixing the magnetization of the spin injector 20 in an anti-parallel direction with respect to the magnetization of the underlayer 16 comprising the magnon gain medium; (B) a voltage is applied across at least one such multilayer column 26 between the top electrode 28 and the bottom electrode 14, wherein the terahertz radiation signal is configured to propagate through the terahertz transparent medium (60 of fig. 12).

In one embodiment of the present technology, the method of generating a terahertz signal by using the apparatus 25 of fig. 11 further comprises: (A1) using the RKKY pinning layer 22 (fig. 1); (A2) the thickness of the RKKY pinned layer is selected to fix the magnetization of the spin injector in an antiparallel orientation with respect to the magnetization of the bottom layer 16 comprising the magnon gain medium.

In one embodiment of the present technology, the method of generating a terahertz signal by using the apparatus 25 of fig. 11 further includes a step (C) of separating each pair of such multilayer columns by a distance L (62 of fig. 12) greater than the wavelength of the generated terahertz signal. In another embodiment of the present technology, referring to fig. 14, a terahertz coherent communication system 1400 can be provided. In certain embodiments, a coherent terahertz illumination beam may be provided to object 1402. In certain embodiments, a coherent terahertz reference beam can be provided to the atmosphere 1404 for use in a terahertz holographic detection and processing system 1406. In one embodiment, a coherent terahertz reference beam can be generated by a split terahertz total-reflection mirror (THz mirror). In another embodiment, the coherent terahertz reference beam can be a second terahertz beam. The terahertz holographic detection and processing system 1406 can include, for example, a terahertz detector, a terahertz beam illuminator, a processing unit, and/or a display. In certain embodiments, a coherent terahertz illumination beam may be generated and/or received. A coherent terahertz illumination beam may illuminate object 1402. Furthermore, a coherent terahertz reference beam can be generated and/or received. Two received coherent terahertz beams (e.g., a coherent terahertz illumination beam and a coherent terahertz reference beam) can be combined to form a holographic image of object 1402. The holographic image of object 1402 may be illuminated, for example, by a terahertz reading beam configured to read the holographic image of object 1402. Additionally, a holographic image of object 1402 can be displayed on a computer-readable display of terahertz holographic detection and processing system 1406. In certain embodiments, the frequency of the coherent terahertz magnon laser can be tuned to enable the coherent terahertz laser beam to propagate through the propagation window of the atmosphere 1404. In certain embodiments, a terahertz holographic image can be recorded on a terahertz multilayer material.

(the following discussion is taken from Wikipedia):

"temporal coherence is a measure of the average correlation between the wave value of the delay τ and itself at any time. Temporal coherence tells us how monochromatic a source is. In other words, it characterizes the degree of interference that a wave interferes with itself at different times. The delay with which the phase or amplitude drifts by a significant amount (and therefore the correlation is significantly reduced) is defined as the coherence time τ_c. At a delay of τ -0, the degree of coherence is perfect, while as the delay exceeds τ - τ_cIt will drop significantly. Coherence length L_cDefined as the wave at time τ_cOf the propagation distance. "

Care should be taken not to confuse the coherence time with the duration of the signal, nor the coherence length with the coherence region.

The terahertz magnon laser system utilizing the time coherence characteristic comprises a single terahertz magnon laser, a terahertz receiver and a processing unit.

Can prove thatIt is clear that the larger the frequency range Δ f that a wave contains, the faster the wave decorrelation (hence τ)_cThe smaller). Thus, there is a trade-off:

τ_cΔ f ≦ 1 (equation 41)

Formally, this follows the convolution theorem in mathematics that relates the Fourier transform of a power spectrum (the intensity at each frequency) to its autocorrelation

An example of temporal coherence. We consider four examples of temporal coherence.

According to the above relationship, a wave containing only a single frequency (monochromatic) is fully correlated with itself at all time delays. Conversely, a wave with a fast drift in phase will have a shorter coherence time.

Similarly, the pulses of the wave (wave packets) naturally have a wide frequency range, and therefore a short coherence time, since the amplitude of the wave changes very quickly.

Finally, white light has a wide frequency range and is a wave with very fast amplitude and phase changes. It is generally called incoherent since it therefore has a very short coherence time (only around 10 cycles).

The monochromatic source is typically a laser; such high monochromaticity means long coherence lengths (up to several hundred meters). For example, a stable single mode he — ne laser can easily produce light with a coherence length of 300 m.

However, not all lasers are monochromatic (e.g., Δ λ ≈ 2 nm-70 nm for mode-locked titanium sapphire lasers). Light emitting diodes are characterized by Δ λ ≈ 50nm, whereas tungsten lamps exhibit Δ λ ≈ 600nm, and therefore the coherence time of these light sources is shorter than that of most monochromatic lasers. Holography requires light of long coherence time.

In contrast, the classic version of optical coherence tomography uses light with a shorter coherence time.

In optics, temporal coherence is measured in an interferometer such as a Michelson interferometer (Michelson interferometer) or a Mach-Zehnder interferometer (Mach-Zehnder interferometer). In these devices, the wave is combined with a self-copy of the delay time τ. The detector measures the time-averaged intensity of the light leaving the interferometer. The resulting interference visibility gives the temporal coherence of the delay τ. Since the coherence time is much shorter than the temporal resolution of any detector for most natural sources, the detector itself will be time averaged.

Spatial coherence

A coherent terahertz magnon laser system utilizing spatial coherence includes at least two coherent terahertz magnon lasers generating two coherent terahertz laser beams, which are received by a terahertz receiver, which combines the two beams to obtain a hologram image.

In some systems, such as water waves or optical systems, the wave-like state may be expanded to one or two dimensions. Spatial coherence describes the ability of two points in space x1 and x2 to interfere within the range of a wave, when averaged over time. More precisely, spatial coherence is the cross-correlation between two points in a wave at all times. A wave is spatially completely coherent if it has only 1 amplitude value over an infinite range of lengths. The extent of the separation between two points in the presence of significant interference defines the diameter A of the coherent region_c(coherence length, which is usually a characteristic of the source, and is usually an industry term related to the coherence time of the source, not the coherence region in the medium.) A_cIs a relevant coherence type of Young's double-slit interferometer (Young's double-slit interferometer). It is also used in optical imaging systems, especially in astronomical telescopes of various types. Sometimes, one also uses "spatial coherence" to refer to the visibility of a wave-like state when combined with a copy of itself moving in space.

Consider a tungsten bulb filament. Different points in the filament emit light independently and have no fixed phase relationship. In detail, at any point in time, the profile of the emitted light is distorted. The profile will vary randomly with coherence time. Since white light sources such as bulbs are small, the filament is considered to be a spatially incoherent light source. In contrast, radio antenna arrays have great spatial coherence because the antennas at the two ends of the array transmit in a fixed phase relationship. The light waves produced by a laser typically have a high temporal and spatial coherence (although the degree of coherence depends to a large extent on the exact characteristics of the laser). The spatial coherence of the laser beam is also manifested as speckle patterns (diffraction fringes) and diffraction fringes seen at the shadow edges.

Holography requires temporally and spatially coherent light. Its inventor danis Gabor (Dennis Gabor) successfully made holograms more than ten years before the laser invention. To produce coherent light, he passed monochromatic light from the mercury vapor lamp emission line through a pinhole spatial filter.

Holography

Coherent superposition of light wave fields includes holography. Holographic objects are commonly used in banknotes and credit cards in everyday life.

Non-optical wave field

A further application relates to coherent superposition of non-optical wave fields. For example, in quantum mechanics, we consider a probability field, which is related to the wave function (interpretation: density of probability amplitudes). Applications here relate to future techniques of quantum computing and already available quantum cryptography techniques and the like.

Quantum cryptography is the science of using quantum mechanical properties to perform cryptographic tasks. The best-known example of quantum cryptography is quantum key distribution, which provides a theoretically secure solution to the problem of key exchange. Quantum cryptography is advantageous in that it allows various cryptographic tasks to be accomplished using only classical (i.e., non-quantum) softened objects (bated objects) that are not proven or speculated to be possible.

In one embodiment of the present technology, a terahertz holographic image of an object can be recorded on a terahertz multilayer material.

Example nine. The layered tungsten disulfide crystal can be used for recording terahertz holographic images. Please see "Terahertz surface emission of d-band electrons from a layer of long discrete crystal by the surface field", Longhui Zhang, Yuanyuuan Huang, Qiyi Zhao, Lipen Zhu, Zehan Yao, Yixuan Zhou, Wanyi Du, and Xinlong Xu; Phys.Rev.B 96,155202 and 2017, 10 and 6.

The above discussion has set forth operations of various exemplary systems and devices, as well as various embodiments relating to exemplary methods of operating such systems and devices. In various embodiments, one or more steps of a method of implementation (e.g., calculating an optimal voltage bias) are performed by a processor under the control of computer-readable and computer-executable instructions. Thus, in some embodiments, the methods are computer-implemented.

In one embodiment, the computer-readable and computer-executable instructions may reside on a computer usable/readable medium.

Thus, computer-executable instructions, such as program modules, executed by a computer may be used to control or implement one or more operations of the various embodiments. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Moreover, the techniques may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.

Although specific steps of exemplary implementations methods are disclosed herein, these steps are examples of steps that may be performed in accordance with various exemplary embodiments. That is, embodiments disclosed herein are well suited to performing various other steps or variations of the steps recited. Further, the steps disclosed herein may be performed in an order different than presented, and not all steps need necessarily be performed in a particular embodiment.

Although various electronic and software-based systems are discussed herein, these systems are merely examples of environments that may be utilized and are not intended to suggest any limitation as to the scope of use or functionality of the technology. Neither should such systems be interpreted as having any dependency or relation to any one or combination of components or functions illustrated in the disclosed examples.

Although the subject matter has been described in language specific to structural features and/or methodological acts, the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims (29)

1. An apparatus for generating coherent terahertz radiation, comprising:

one or more multi-layered tunable microcolumns, each of which further comprises:

a substrate;

a bottom electrode;

a bottom layer of ferromagnetic material, further comprising a Magnon Gain Medium (MGM) coupled to the bottom electrode;

a tunnel junction coupled to the ferromagnetic material;

a spin injector coupled to the tunnel junction;

a pinning layer coupled to the spin injector;

a reference layer coupled to the pinned layer; and

a top electrode;

and

and the accommodating cavity surrounds at least one multilayer adjustable microcolumn.

2. The apparatus of claim 1, wherein the receiving cavity includes a first aperture configured to output the coherent terahertz radiation.

3. The apparatus of claim 2, further comprising: a storage chamber surrounding the receiving chamber.

4. The apparatus of claim 3, wherein the storage chamber is larger in size than the corresponding size of the receiving chamber.

5. The device of claim 3, wherein the storage chamber comprises a second aperture configured to output coherent terahertz radiation.

6. The device according to claim 1, wherein a bias voltage is applied to at least one of the multilayer tunable microcolumns between the top electrode and the bottom electrode, and the bias voltage is configured to shift the fermi level of the spin injector relative to the fermi level of the ferromagnetic material.

7. The device of claim 6, wherein the ferromagnetic material further comprises a conduction band split into two sub-bands comprising a first sub-band with spins up and a second sub-band with spins down separated by an exchange energy gap, and wherein the first sub-band comprises electrons with spins up polarized in a magnetization direction of the ferromagnetic material, and wherein the second sub-band comprises electrons with spins down polarized in a direction opposite to the magnetization direction of the ferromagnetic material.

8. The device of claim 1, wherein the MGM is configured to carry unbalanced magnons generated by unbalanced electrons, wherein the unbalanced electrons spinning down are injected from the spin injector into the MGM via the tunnel junction.

9. The device of claim 8, wherein the MGM is configured to generate terahertz radiation using the unbalanced magnon.

10. The apparatus of claim 1, wherein the substrate is made of a material selected from the group consisting of: alumina (Al)₂O₃) (ii) a Indium tin oxide (InTnO); silicon (Si); silicon on sapphire (SoS); and magnesium oxide (MgO).

11. The apparatus of claim 1, wherein the bottom electrode is made of a material selected from the group consisting of: cobalt iron alloy (Co)_0.5Fe_0.5) (ii) a Silver (Ag); gold (Au); platinum (Pt); cobalt (Co); palladium (Pd); titanium (Ti); and titanium Tungsten (TiW).

12. The apparatus as recited in claim 1, wherein the MGM is made of a material selected from the group consisting of: chromium dioxide (CrO)₂) (ii) a Half-metal ferromagnetic oxide Sr₂FeMoO₆(ii) a Heusler alloy Co₂MnGe; heusler alloy Co₂Mnsi (cms); heusler alloy Co₂Fesi (cfs); heusler alloy Co₂MnSn; and heusler alloy Co₂FeAl_0.5Si_0.5(CFAS)。

13. The apparatus of claim 1, wherein the tunnel junction is made of a material selected from the group consisting of: magnesium oxide (MgO); alumina (Al)₂O₃) (ii) a And spinel MgAl₂O₄。

14. A method for tuning the frequency of terahertz radiation, comprising:

using a device comprising at least one of the multilayered tunable microcolumns, each of which comprises a spin injector, a tunnel junction, and a Magnon Gain Medium (MGM), wherein at least one of the multilayered tunable microcolumns is enclosed in a containment cavity;

applying a bias voltage to the at least one multi-layered tunable microcolumn to shift the fermi level of the spin injector relative to the fermi level of the MGM to initiate generation of non-equilibrium magnons; wherein the interaction between the unbalanced magnons results in the generation of terahertz radiation;

tuning the frequency of the generated coherent terahertz radiation by changing the bias voltage; and

the accommodating cavity is used for outputting adjustable coherent terahertz radiation.

15. The method of claim 14, further comprising:

a step of modulating the tunable coherent terahertz radiation by modulating the bias voltage with a modulation frequency.

16. A method for tuning the frequency of terahertz radiation, comprising:

using a device comprising at least one of the multilayered tunable microcolumns, each of which comprises a spin injector, a tunnel junction, and a Magnon Gain Medium (MGM), wherein at least one of the multilayered tunable microcolumns is enclosed in a containment cavity; and wherein the receiving chamber is enclosed in the storage chamber;

applying a bias voltage to the at least one multi-layered tunable microcolumn to shift the fermi level of the spin injector relative to the fermi level of the MGM to initiate generation of non-equilibrium magnons; wherein the interaction between the unbalanced magnons results in the generation of terahertz radiation;

tuning the frequency of the generated coherent terahertz radiation by changing the bias voltage;

outputting adjustable coherent terahertz radiation to the storage cavity by using the accommodating cavity; and

and outputting adjustable coherent terahertz radiation by using the storage cavity.

17. The method of claim 16, further comprising:

a step of modulating the tunable coherent terahertz radiation by modulating the bias voltage with a modulation frequency.

18. The method of claim 16, further comprising:

modulating the tunable coherent terahertz radiation by modulating the output coherent radiation by external means.

19. The method of claim 16, further comprising:

a step of modulating the tunable coherent terahertz radiation by modulating the output coherent radiation with a piezoelectric material to mechanically change a size of an output aperture.

20. The method of claim 16, further comprising:

a step of modulating the tunable coherent terahertz radiation by modulating the output coherent radiation with a synthetic ceramic material.

21. A coherent terahertz communication system comprising:

at least one coherent terahertz magnon laser; each of the coherent terahertz magnon lasers is configured to generate a coherent terahertz laser beam; and

a terahertz coherent detection system configured to receive at least one coherent terahertz laser beam and configured to combine each received coherent terahertz laser beam into a combined terahertz beam; the combined terahertz beam is selected from the group consisting of: 3D terahertz images; a terahertz spatial coherent image; terahertz time-coherent images; terahertz time-space coherent images; a terahertz holographic image; and a quantum cryptography image.

22. The coherent terahertz communication system of claim 21, wherein the coherent terahertz magnon laser comprises:

one or more multi-layered tunable microcolumns, each of which further comprises:

a substrate;

a bottom electrode;

a bottom layer of ferromagnetic material, further comprising a Magnon Gain Medium (MGM) coupled to the bottom electrode;

a tunnel junction coupled to the ferromagnetic material;

a spin injector coupled to the tunnel junction;

a pinning layer coupled to the spin injector;

a reference layer coupled to the pinned layer; and

a top electrode;

and

and the accommodating cavity surrounds at least one multilayer adjustable microcolumn.

23. The coherent terahertz communication system of claim 21, wherein the receiving cavity comprises a first aperture configured to output the coherent terahertz radiation.

24. The coherent terahertz communication system of claim 22, further comprising: a storage chamber surrounding the receiving chamber.

25. The coherent terahertz communication system of claim 24, wherein the size of the storage chamber is larger than the corresponding size of the receiving chamber.

26. The coherent terahertz communication system of claim 24, wherein the storage chamber comprises a second aperture configured to output coherent terahertz radiation.

27. A method of coherent terahertz communication employing at least one coherent terahertz magnon laser and a terahertz coherent detection system, comprising:

generating a coherent terahertz irradiation beam; the coherent terahertz radiation beam irradiates an object;

generating a coherent terahertz reference beam;

receiving the coherent terahertz illumination beam illuminating the object;

receiving the coherent terahertz reference beam;

combining the two received terahertz coherent light beams to form a holographic image of the object;

irradiating the holographic image of the object with a terahertz reading beam configured to read the holographic image of the object;

and

displaying the holographic image of the object on a computer readable display.

28. The method of claim 27, wherein the step of generating the coherent terahertz laser beam further comprises the steps of:

the frequency of the coherent terahertz magnon laser is tuned to enable the coherent terahertz laser beam to propagate through a propagation window of the atmosphere.

29. The method of claim 27, wherein the step of displaying the holographic image of the object on a computer readable display further comprises the steps of:

and recording the terahertz holographic image on the terahertz multilayer material.

Images