CN207895171U - Photoswitch based on graphene/metal hybrid construction - Google Patents

Abstract

The utility model discloses an optical switch based on a graphene/metal hybrid structure, which comprises a substrate reflective layer, which is used to reflect incident light; a medium layer, which is arranged on the substrate reflective On layer; Graphene layer, described Graphene layer comprises at least one layer of Graphene, and described Graphene layer is arranged on described medium layer, and described substrate reflection layer, described medium layer and described Graphene layer constitute capacitor structure; metal structure layer, the metal structure layer is arranged on the graphene layer; metal electrodes, the metal electrodes are respectively arranged on the substrate reflection layer and the graphene layer; and voltage source, the A voltage source is respectively connected to the graphene layer and the metal structure layer, and a voltage is applied to the graphene layer through the voltage source to affect the plasmon resonance effect of the metal structure layer. According to the optical switch of the embodiment of the utility model, a metal structure layer is fabricated on the graphene layer, and a voltage is applied to the graphene to change the optical properties of the graphene, thereby affecting the plasmon resonance effect of the metal structure layer, thereby realizing the function of the optical switch.

Description

Optical switches based on graphene/metal hybrid structures

technical field

The present invention relates to the technical field of optical switches, in particular to an optical switch based on a graphene/metal hybrid structure.

Background technique

With the advancement of science and technology and the development of modernization, the size requirements of optoelectronic components are becoming more and more precise, and nanophotonics provides the possibility for the integration of optical devices. Nanophotonics uses the optical near-field as the information carrier, and realizes the regulation of the phase, amplitude, polarization, transmittance and other parameters of light through the electromagnetic interaction between the micro-nano-sized optical elements and the near-field. At present, there are two main approaches to optical manipulation at the nanometer scale. One is based on photonic crystals, which regulate the optical transmission path through the control of the internal structure of photonic crystals, so as to realize the transmission, modulation and optical interconnection of optical information. Typical representatives are Nano-microcavity, optical waveguide and optical splitting device. Most of the structures of photonic crystals are three-dimensional, which poses great challenges to the design and fabrication of photonic crystals. Another way to regulate light is to control the propagation of Surface Plasmon Polarizations (SPP), which are generated on the surface of metals and dielectrics and are mixed excited states caused by the resonance of light and free electrons on the metal surface. , is also an electromagnetic wave. By designing different metal structures on the medium, surface plasmon waves can be effectively excited and the resonance effect of plasmons can be realized, so that parameters such as transmittance, amplitude, and phase of incident light can be realized on a two-dimensional plane. regulation. Since designing the structure of the metal and the medium can realize the change of the incident light transmittance, we can design the structure to realize the change of the metal to the incident light transmittance. Can form the effect of optical switch.

Graphene, a planar film of six-membered rings formed by sp2 hybridization of carbon atoms, is a two-dimensional material with a thickness of only one atomic layer. Graphene is a new type of nanomaterial. Due to its excellent strength, flexibility, electrical conductivity, thermal conductivity, and optical properties, it has been greatly developed in the fields of physics, materials science, electronic information, computers, and aerospace. In the field of optics, we found that graphene has the property of adjustable refractive index. Specifically, the electrical conductivity of graphene is changed by applying voltage to graphene, thereby realizing the change of refractive index. The conductivity of graphene is related to the Fermi energy level of graphene, and the Fermi energy level of graphene can be effectively changed by applying voltage (electrical doping). Therefore, graphene is an excellent voltage-tunable material.

Prior to the present invention, a Chinese invention patent (CN107121793A) is a surface plasmon optical switch based on a periodic subwavelength hole array. Plasmon resonance is achieved by designing metal nanohole arrays on dielectric substrates. By designing the parameters of the fixed hole array, the incident light in one polarization direction can resonate, and the other incident polarized light has no resonance effect, so that the effect of light switching can be realized by changing the polarization angle of the incident light. The invention implements the function of an optical switch by changing the incident polarization angle, and does not relate to an optical switch for incident light of the same polarization.

Chinese invention patent (CN107329209A) M*N multicast transmission optical switch, through the integration of low refractive index difference optical splitter array and high refractive index optical switch array, the multicast transmission optical switch is obtained by using waveguide arrays of different materials . The invention adopts multiple waveguides to realize the switching function, and does not involve the optical switch of the planar structure.

Chinese invention patent (CN106873082A) A split resonant ring metamaterial optical switch, the structure is a base of ceramic materials and a split resonator ring, using the characteristics that the optical excitation can cause the dielectric constant of the ceramic material to change, so that the resonant frequency or resonance of the split resonator ring The intensity changes to realize the function of optical switch. This invention utilizes the change of material properties caused by incident light, and cannot realize real-time switch regulation.

Contents of the invention

The present invention aims to solve one of the above-mentioned technical problems at least to a certain extent.

Therefore, the object of the present invention is to propose an optical switch based on a graphene/metal hybrid structure that can change the transmittance of incident light in real time through voltage regulation.

The optical switch based on graphene/metal hybrid structure according to the embodiment of the present invention comprises: a substrate reflection layer, the substrate reflection layer is used to reflect incident light; a dielectric layer, the dielectric layer is arranged on the substrate reflection layer On layer; Graphene layer, described Graphene layer comprises at least one layer of Graphene, and described Graphene layer is arranged on described medium layer, and described substrate reflection layer, described medium layer and described Graphene layer constitute capacitor structure; metal structure layer, the metal structure layer is arranged on the graphene layer; metal electrodes, the metal electrodes are respectively arranged on the substrate reflection layer and the graphene layer; and voltage source, the A voltage source is connected to the graphene layer, and a voltage is applied to the graphene layer through the voltage source to affect the plasmon resonance effect of the metal structure layer.

According to the optical switch based on the graphene/metal hybrid structure of the embodiment of the present invention, the capacitive structure is formed by the substrate reflective layer, the dielectric layer and the graphene layer, and a voltage source is used to apply a voltage to the graphene layer to affect the metal structure layer. The plasmon resonance effect can further adjust the transmittance by changing the external applied voltage. When the external voltage is two different values, the device shows the "on" and "off" states for the incident light. Specifically, by combining the metal structure and graphene to form a metal structure/graphene/medium hybrid structure, the function of regulating the incident light is realized. Among them, the metal structure layer can adjust the transmittance of incident light of a certain wavelength through the plasmon resonance effect, and adjust the graphene through the voltage, so that the graphene has different refractive indices, thereby changing the metal structure plasmon. The resonant wavelength makes the entire structure have two cases of transmittance of 0 and not 0 under the same incident light condition, thereby realizing the function of an optical switch.

In addition, the optical switch based on the graphene/metal hybrid structure according to the embodiment of the present invention may also have the following additional technical features:

According to an embodiment of the present invention, the substrate reflective layer is metal.

According to an embodiment of the present invention, the reflective layer of the substrate is gold, silver or aluminum.

According to an embodiment of the present invention, the dielectric layer is aluminum oxide, boron nitride, magnesium fluoride or silicon dioxide, and the thickness of the dielectric layer is 0-2um.

According to an embodiment of the present invention, the number of graphene layers is 1-15 layers.

According to an embodiment of the present invention, the voltage applied by the voltage source is 0-200v.

According to an embodiment of the present invention, the material of the metal structure layer is at least one of gold, silver, aluminum, nickel, chromium, titanium and copper or an alloy thereof.

According to an embodiment of the present invention, the metal structure layer is a metal grating, the period of the metal grating is 150nm-10μm, the duty ratio is 0.2-0.9, and the height is 10nm-200nm.

According to an embodiment of the present invention, the shape of the metal grating is at least one of rectangle, trapezoid and regular triangle or a combination thereof.

According to an embodiment of the present invention, the graphene layer is tiled on the dielectric layer.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is a schematic structural view of an optical switch based on a graphene/metal hybrid structure according to an embodiment of the present invention;

Fig. 2 is the Fermi level diagram of graphene;

3 is a graph showing the relationship between reflectivity and wavelength at different Fermi levels when an optical switch based on a graphene/metal hybrid structure does not have a graphene layer according to an embodiment of the present invention;

Fig. 4 (a) is the graphene layer of the graphene layer based on the optical switch of graphene/metal hybrid structure according to the embodiment of the present invention is the reflectivity and the wavelength relation figure under different Fermi energy level when single layer;

Fig. 4 (b) is the graphene layer of the graphene layer based on the optical switch of graphene/metal hybrid structure according to the embodiment of the present invention is 5 layers, the reflectivity and the wavelength relation diagram under different Fermi levels;

4( c ) is a graph showing the relationship between reflectivity and wavelength at different Fermi levels when the graphene layer of the optical switch based on the graphene/metal hybrid structure according to an embodiment of the present invention has 10 layers.

Reference signs:

Optical switch 100 based on graphene/metal hybrid structure;

Substrate reflective layer 10; dielectric layer 20; graphene layer 30; metal structure layer 40; metal electrode 50.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

In describing the present invention, it is to be understood that the terms "center", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", The orientation or positional relationship indicated by "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the referred device or element Must be in a particular orientation, be constructed in a particular orientation, and operate in a particular orientation, and therefore should not be construed as limiting the invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

The optical switch 100 based on a graphene/metal hybrid structure according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1 , an optical switch 100 based on a graphene/metal hybrid structure according to an embodiment of the present invention includes a substrate reflection layer 10 , a dielectric layer 20 , a graphene layer 30 , a metal structure layer 40 and a voltage source.

Specifically, the substrate reflective layer 10 is used to reflect incident light, the dielectric layer 20 is disposed on the substrate reflective layer 10, the graphene layer 30 includes at least one layer of graphene, the graphene layer 30 is disposed on the dielectric layer 20, and the substrate The reflective layer 10, the dielectric layer 20 and the graphene layer 30 constitute a capacitor structure, the metal structure layer 40 is arranged on the graphene layer 30, the metal electrodes 50 are respectively arranged on the substrate reflective layer 10 and the graphene layer 30, the voltage source and the graphene layer The layer 30 is connected, and a voltage is applied to the graphene layer 30 by a voltage source to affect the plasmon resonance effect of the metal structure layer 40 .

It should be noted that the voltage source is a tunable voltage source.

Thus, according to the optical switch 100 based on the graphene/metal hybrid structure of the embodiment of the present invention, the capacitive structure is formed by the substrate reflective layer 10, the dielectric layer 20 and the graphene layer 30, and the graphene layer 30 is supplied with a voltage source. Apply a voltage to affect the plasmon resonance effect of the metal structure layer 40, and then adjust the transmittance by changing the external applied voltage. When the external voltage is two different values, the device presents "on" and "off" to the incident light. ” state without re-changing the parameters of the structure, realizing the function of real-time regulation.

According to an embodiment of the present invention, the substrate reflection layer 10 is metal.

Optionally, the substrate reflective layer 10 can be metal such as gold, silver or aluminum, and the substrate reflective layer 10 can realize the function of a mirror to reflect the incident light at most. Generally, a metal film can be used as the substrate reflective layer 10 .

According to an embodiment of the present invention, the dielectric layer 20 can be a common dielectric such as aluminum oxide, boron nitride, magnesium fluoride, or silicon dioxide, and the thickness of the dielectric layer 20 can be 0-2 um, or even tens of nanometers.

Optionally, the number of layers of the graphene layer 30 is 1-15 layers, and the graphene layer 30 may be a single layer or multiple layers, and the graphene layer 30 may be flatly laid on the dielectric layer 20 .

Preferably, the voltage applied by the voltage source is 0-200v, and the voltage source may include a metal electrode 50, and the metal electrode 50 is placed on the substrate reflective layer 10 and the graphene layer 30 respectively.

According to an embodiment of the present invention, the material of the metal structure layer 40 is at least one of gold, silver, aluminum, nickel, chromium, titanium and copper or an alloy thereof.

In some embodiments of the present invention, the metal structure layer 40 is a metal grating, the period of the metal grating is 150 nm-10 μm, the duty ratio is 0.2-0.9, and the height is 10 nm-200 nm.

Optionally, the shape of the metal grating may be at least one of rectangle, trapezoid and regular triangle or a combination thereof.

According to an embodiment of the present invention, the graphene layer 30 can be tiled on the dielectric layer 20 .

It should be noted that the principle of the optical switch 100 based on the graphene/metal hybrid structure according to the embodiment of the present invention is: there are free electrons in the metal, and a specific metal structure can generate a plasmon resonance effect at a specific incident light frequency. Therefore, a superabsorption can be realized at the corresponding resonance wavelength, and this superabsorption makes all the passing light absorbed, presenting an "off" state. By selecting a suitable metal and manufacturing a suitable metal micro-nano structure, superabsorption in a specific wavelength band can be achieved, so that the transmittance (or reflectance) of the incident light is 0, and the optical path is in an "off" state.

Graphene is a two-dimensional flat film composed of carbon atoms. Due to its special energy band structure, graphene can exhibit different optical refractive indices when different voltages are applied to it. Graphene can be considered as a tunable material by applying different voltages. According to the optical switch 100 based on the graphene/metal hybrid structure of the embodiment of the present invention, the graphene layer 30 is placed under the metal structure layer 40, and the tunable graphene can affect the plasmon resonance of the metal. Applying different voltages can change the resonant frequency of metal plasmons. When the resonant frequency is far away from the operating frequency, there is no superabsorption, and it is in an "on" state. Furthermore, by applying different voltages to the graphene, a photoelectric switch was obtained.

The shape, period, duty ratio, and thickness of the dielectric layer of the metal structure are theoretically calculated according to the required working wavelength, and are calculated according to the finite difference time domain method or strict coupled wave theory. At the required working wavelength, the Fermi energy level required by graphene is obtained when the maximum and minimum values of transmission (or reflection) are obtained.

The optical switch 100 based on the graphene/metal hybrid structure according to the present invention will be described below with reference to the accompanying drawings and specific embodiments.

As shown in FIG. 1 , metallic silver is used as the substrate reflective layer 10 , and the thickness of the substrate reflective layer 10 is set to two microns to ensure high reflectivity. Aluminum oxide (Al ₂ O ₃ ) is set on the substrate reflective layer 10 as the dielectric layer 20, and the thickness of the dielectric layer 20 is 21nm. On the aluminum oxide, 10 layers of graphene are tiled as the graphene layer 30. On the graphene A silver grating with a period of 250 nm, a grating width of 160 nm, and a height of 10 nm is provided on the layer 30 as the metal structure layer 40 .

The optical switch 100 based on the graphene/metal hybrid structure according to the embodiment of the present invention is simulated by using FDTD (Finite-Difference Time-Domain Solutions) software based on the finite difference time domain method, with 1550nm as the working wavelength and TM polarized light For incident light, the role of an optical switch based on a graphene/metal hybrid structure is realized.

As shown in Figure 2, the energy band diagram of graphene is a Dirac cone, and when a voltage is applied to graphene, the Fermi energy level of graphene can be changed.

As shown in Figure 3, when the incident light enters the metal structure layer 40, plasmon resonance can be generated to form a resonance peak. However, after the metal structure layer 40 is fabricated, the structural parameters cannot be changed, so the real-time switching cannot be achieved. Function.

As shown in Figures 4(a) to 4(c), after the introduction of graphene, different resonance peaks are obtained at different Fermi levels. The ability to adjust the position of different resonance peaks is also closely related to the number of layers of graphene. The ability to adjust the graphene single layer (Fig. 4(a)) and 5 layers (Fig. 4(b)) was compared respectively. At 1550nm wavelength, when the number of graphene layers is 10 layers (Fig. 4(c)), when the Fermi energy level is 0.695eV, the optical switch 100 based on the graphene/metal hybrid structure is in the off state, when the Fermi energy level When the level is 0.9eV, the optical switch 100 based on the graphene/metal hybrid structure has a high reflectivity, showing an on state.

In summary, compared with the prior art, the optical switch 100 based on the graphene/metal hybrid structure according to the embodiment of the present invention has the following advantages:

(1) Using graphene that can be electrically regulated, the optical switch 100 device based on the graphene/metal hybrid structure can be turned on or off by simply adjusting the externally applied voltage, without re-changing the parameters of the structure, realizing real-time Regulatory function;

(2) The control range of graphene is wide, and the switching effect of multiple wavelengths can be realized on an optical switch 100 device based on a graphene/metal hybrid structure through voltage regulation;

(3) By changing the structure of the metal, combined with the tunability of the optical properties of graphene, it is possible to achieve the near-infrared to mid-infrared switching function (1000nm-10um).

It should be noted that, compared with CN107121793A, the optical switch 100 based on the graphene/metal hybrid structure of the embodiment of the present invention is aimed at a kind of polarized light, and changes the Fermi level of graphene through voltage regulation to realize the optical switch. Function. Compared with CN107329209A, the optical switch 100 based on the graphene/metal hybrid structure of the embodiment of the present invention uses a planar structure to realize the function of an optical switch instead of using a waveguide structure with a length, which can be thinner and more conducive to Integration of devices such as optical chips. Compared with CN106873082A, the optical switch 100 based on the graphene/metal hybrid structure of the embodiment of the present invention can be turned on or off in real time by voltage regulation.

Other configurations and operations of the optical switch according to the embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limitations to the present invention. Variations, modifications, substitutions, and modifications to the above-described embodiments are possible within the scope of the present invention.

Claims (10)

1. a kind of photoswitch based on graphene/metal hybrid construction, which is characterized in that including：

Substrate reflection layer, the substrate reflection layer is for reflecting incident light；

Dielectric layer, the dielectric layer are located on the substrate reflection layer；

Graphene layer, the graphene layer include at least one layer of graphene, and the graphene layer is located on the dielectric layer, described Substrate reflection layer, the dielectric layer and the graphene layer constitute capacitance structure；

Structured metal layer, the structured metal layer are located on the graphene layer；

Metal electrode, the metal electrode are respectively arranged on the substrate reflection layer and the graphene layer；And

Voltage source, the voltage source are connect with the graphene layer, apply voltage to the graphene layer by the voltage source To influence the plasma resonance effect of the structured metal layer.

2. the photoswitch according to claim 1 based on graphene/metal hybrid construction, which is characterized in that the substrate Reflecting layer is metal.

3. the photoswitch according to claim 2 based on graphene/metal hybrid construction, which is characterized in that the substrate Reflecting layer is gold, silver or aluminium.

4. the photoswitch according to claim 1 based on graphene/metal hybrid construction, which is characterized in that the medium Layer is aluminium oxide, boron nitride, magnesium fluoride or silica, and the thickness of the dielectric layer is 0-2um.

5. the photoswitch according to claim 1 based on graphene/metal hybrid construction, which is characterized in that the graphite The number of plies of alkene layer is 1-15 layers.

6. the photoswitch according to claim 1 based on graphene/metal hybrid construction, which is characterized in that the voltage The voltage that source applies is 0-200V.

7. the photoswitch according to claim 1 based on graphene/metal hybrid construction, which is characterized in that the metal The material of structure sheaf is at least one of gold, silver, aluminium, nickel, chromium, titanium and copper or its alloy.

8. the photoswitch according to claim 7 based on graphene/metal hybrid construction, which is characterized in that the metal Structure sheaf is metal grating, and the period of the metal grating is 150nm-10 μm, and it is 0.2-0.9 to account for wide ratio, is highly 10nm- 200nm。

9. the photoswitch according to claim 8 based on graphene/metal hybrid construction, which is characterized in that the metal The shape of grating is rectangle, at least one of trapezoidal and equilateral triangle or a combination thereof.

10. according to any photoswitch based on graphene/metal hybrid construction in claim 1-9, which is characterized in that The graphene layer is laid on the dielectric layer.