CN212873134U - Near-infrared broadband optical switch device coupled by graphene - Google Patents
Near-infrared broadband optical switch device coupled by graphene Download PDFInfo
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- CN212873134U CN212873134U CN202021767611.6U CN202021767611U CN212873134U CN 212873134 U CN212873134 U CN 212873134U CN 202021767611 U CN202021767611 U CN 202021767611U CN 212873134 U CN212873134 U CN 212873134U
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Abstract
本实用新型公开了一种利用石墨烯耦合的近红外宽波段光开关装置，包括：衬底，以及覆盖在衬底上的调制层，调制层上通过光刻‑镀膜设有介质层和金属纳米圆柱阵列，金属纳米圆柱阵列作为电极一，调制层上通过镀膜设有电极二，调制层为石墨烯；石墨烯层直接生长或者转移至衬底上，所述石墨烯层上施加有垂直方向的直流偏置电压，介质层的材料为光刻胶，光刻胶通过旋涂机旋涂于调制层的上方，通过二次双光束全息光刻工艺形成介质层，本实用新型提供一种利用石墨烯耦合的近红外宽波段光开关装置，以解决现有石墨烯光开关调制深度较低和制备复杂的问题，实现了一种与入射偏振无关，结构和制备相对简单，具有优异调制深度和调制带宽的反射式光开关。
The utility model discloses a near-infrared broadband optical switch device utilizing graphene coupling, comprising: a substrate, and a modulation layer covering the substrate; Cylinder array, metal nano-cylindrical array is used as electrode one, electrode two is provided on the modulation layer by coating, and the modulation layer is graphene; the graphene layer is directly grown or transferred to the substrate, and the graphene layer is applied with a vertical direction. DC bias voltage, the material of the medium layer is photoresist, the photoresist is spin-coated on the top of the modulation layer by a spin coater, and the medium layer is formed by a secondary double-beam holographic lithography process. A graphene-coupled near-infrared broadband optical switch device to solve the problems of low modulation depth and complex preparation of the existing graphene optical switch, and realizes an incident polarization-independent, relatively simple structure and preparation, with excellent modulation depth and modulation. Broadband reflective optical switch.
Description
Technical Field
The utility model relates to an optical device field especially relates to an utilize near-infrared broadband optical switch device of graphite alkene coupling.
Background
With the rapid development of the optical communication industry, micro-nano optoelectronic devices are widely concerned by people due to the advantages of excellent performance, ultra-small volume and integration with optical fibers. Graphene has excellent optical and electrical properties as a tunable material, and the electric tuning rate of graphene can reach GHz in an external voltage mode by virtue of the ultrahigh carrier mobility, so that the graphene is applied to ultra-fast photoelectric devices such as photoelectric detectors and the like, and the application of the graphene in the field of optical communication is receiving more and more attention.
Due to the special optical property of graphene, in the middle infrared to terahertz wave band, the absorption and local effect of graphene surface plasmas on an electromagnetic field can be enhanced by exciting the graphene surface plasmas, and then the electromagnetic field can be regulated and controlled. However, in the visible light to near infrared band (including the optical communication band), graphene cannot excite surface plasmon, which makes it difficult for graphene to realize adjustment and manipulation of the device through surface plasmon polariton in the optical communication band.
In order to improve the absorption rate of graphene to visible light and near-infrared band electromagnetic waves, the absorption capacity of graphene to incident light is often enhanced by combining graphene with a resonant cavity or a photonic crystal and by means of multiple reflection or photon localization in the cavity. For example: the light modulator based on the graphene super capacitor, which is proposed by the Polat et al, takes graphene as two parallel electrode plates of a capacitor, and the middle of the capacitor is filled with electrolyte. Incident light enters the structure and then is reflected between the two graphene electrode plates for multiple times, so that the absorption of the graphene to light is enhanced. When different bias voltages are applied to two ends of the Graphene, the absorption rate of the Graphene changes, so that the Optical transmittance modulation depth of 35% in a wavelength band of 450nm to 2m is realized (see [ Emre o.flat, et. al., "Broadband Optical Modulators Based on Graphene Supercapacitors", Nano Letters, vol.13, No. (12), pp.5851-5857,2013 ]). On the surface, a micro-nano structure super surface can be introduced, and interaction between graphene and light is improved. For example: cai et al introduce graphene into a metal slit-dielectric-metal (MDM) -based surface plasmon resonance structure, and change the optical properties (dielectric constant) of the graphene by adjusting the fermi level of the graphene can significantly adjust the coupling effect of the adjacent metal slits and the MDM cavity inner surface plasmon, thereby adjusting the resonance absorption wavelength of the absorber, performing reflection modulation on TM incident light, achieving perfect absorption in the near infrared (1000-. (see [ YIjun Cai, et. al., "Enhanced spatial near-amplified modulation of graphene-loaded pixel absorbers using plasma nanoslips", Optics Express, vol.23, No. (25), pp. 32318-. In the front of the present invention, chinese utility model patent (CN108563040A) is based on a graphene/metal hybrid optical switch. The graphene is placed in a metal-medium-metal structure, interaction between light and the graphene is enhanced by using the resonant cavity, and the optical property of the graphene is changed by applying direct-current bias voltage to the graphene, so that the position of a plasma resonance peak of a metal grating is influenced, and the function of optical switching is realized on TM linear polarized light. But the function of the optical switch can be realized only for a single wavelength, the metal grating structure increases the dependence on the polarization state of incident light, and the difficulty of preparation and application is greatly increased by etching the metal grating.
Although the optical device based on the graphene has a certain adjusting capacity, the optical device has a certain dependence on the polarization state of incident light, and the modulation depth and the application prospect of the graphene optical switch are limited by the weak interaction between the graphene and an electric field and the complex preparation process.
Disclosure of Invention
The utility model overcomes prior art's is not enough, provides an utilize near-infrared broadband optical switch device of graphite alkene coupling.
In order to achieve the above purpose, the utility model adopts the technical scheme that: a near-infrared broadband optical switching device using graphene coupling, comprising: a substrate, and a modulation layer overlying the substrate, characterized in that: a dielectric layer and a metal nano-cylinder array are arranged on the modulation layer through photoetching-coating, the metal nano-cylinder array is used as a first electrode, an electrode II is arranged on the modulation layer through coating, and the modulation layer is graphene; at least one layer of the graphene is directly grown or transferred onto the substrate; the material of the dielectric layer is photoresist, the photoresist is coated on the modulation layer in a spin coating mode through a spin coating machine to form a uniform photoresist film, and the dielectric layer is formed through a secondary double-beam holographic photoetching process.
In a preferred embodiment of the present invention, the metal nano-cylinder array is made of aluminum.
In a preferred embodiment of the present invention, the aluminum metal is deposited on the upper surface of the dielectric layer uniformly by a coating process, and covers and wraps the dielectric layer completely.
In a preferred embodiment of the present invention, the second electrode is deposited on the top of the modulation layer not covered by the nano-cylinder array.
In a preferred embodiment of the present invention, the second electrode is made of gold, silver or copper.
In a preferred embodiment of the present invention, the substrate is made of silicon dioxide.
In a preferred embodiment of the present invention, a dc bias voltage in a vertical direction is applied to the graphene layer.
In a preferred embodiment of the present invention, the modulation depth of the optical switch is defined as:
wherein R isonAnd RoffRespectively the reflectivity when the optical switch is open and closed.
In a preferred embodiment of the present invention, the number of graphene layers is 15.
In a preferred embodiment of the present invention, the thickness of the dielectric layer is 190 nm.
In a preferred embodiment of the present invention, the metal nano-cylinder array has a period of 250nm and a diameter of 200 nm.
In a preferred embodiment of the present invention, the optical switch structure is within the range of 1400-1700 nm.
In a preferred embodiment of the present invention, the modulation depth of the optical switch can reach up to 99.77% (26.35 dB).
The utility model provides a defect that exists among the background art, the utility model discloses possess following beneficial effect:
(1) the utility model provides a near-infrared broadband light switch based on graphite alkene absorption enhancement utilizes metal aluminium cylinder array can be aroused magnetic plasma resonance effect with the modulation layer and the coupling of metal nanometer cylinder array of graphite alkene, and under the magnetic plasma resonance effect condition, graphite alkene is showing the absorption that the enhancement leads to graphite alkene with the interact of incident light and is showing and increasing for the reverberation is showing and is reducing.
(2) In the utility model, when the Fermi level of the graphene is changed, the dielectric constant of the graphene is changed, so that the frequency and amplitude of the magnetic resonance effect of the metal aluminum cylindrical array are changed, the function of the optical switch is realized, and the modulation depth of the optical switch is further increased;
because the structure adopts the two-dimensional aluminum cylinder array, the two orthogonal polarization directions (TE light and TM light) of the incident light are symmetrical, and the incident light in any polarization state can be decomposed into the two orthogonal TE light and TM light, the optical switch function of the structure is independent of the polarization state of the incident light (no matter the incident light is the TE light, the TM light or the natural light);
meanwhile, the structure can be realized by combining large-area ultraviolet exposure with metal coating, ion etching on metal is not needed, and the experimental preparation difficulty is greatly reduced.
(3) The optical switch of the utility model has the modulation depth larger than 91.36% (10.63dB) in the communication wave band of 1400-1700nm, and can reach 99.77% (26.35dB) at most.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts;
FIG. 1 is a perspective view of a preferred embodiment of the present invention;
FIG. 2 is a cross-sectional view of two units of a preferred embodiment of the invention cut along the diameter of a circular hole;
fig. 3(a), 3(b), and 3(c) are graphs of the reflectance and absorbance spectra with graphene (no voltage applied) and without graphene in the present invention;
FIG. 4 is a graph of reflectance at Fermi level of 0.5-3.0 μm for a graphene optical switch according to the present invention;
fig. 5(a), 5(b), 5(c) are graphs of the reflectivity of the preferred embodiment of the present invention as a function of the structure size;
fig. 6 is a graph of reflectance versus the number of graphene layers for a preferred embodiment of the present invention;
FIG. 7 is a graph of reflectivity of a graphene optical switch at a Fermi level of 1400-1700nm according to the present invention;
in the figure: 1. a substrate; 2. a modulation layer; 3. a dielectric layer; 4. a metal nano cylinder array (electrode one); 5. and a second electrode.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Reference throughout this specification to "an embodiment," "one embodiment," "some embodiments," or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of "an embodiment," "one embodiment," or "some embodiments" are not necessarily all referring to the same embodiments. If the specification states a component, feature, structure, or characteristic "may", "might", or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, that does not mean there is only one of the element. If the specification or claim refers to "a further" element, that does not preclude there being more than one of the further element.
In the description of the present invention, unless otherwise specified the use of the ordinal adjectives "first", "second", and "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner. In the description of the invention, unless otherwise specified, "a plurality" means two or more.
As shown in fig. 1 and 2, a near-infrared broadband optical switch device using graphene coupling includes: the device comprises a substrate 1, wherein a modulation layer 2 covers the substrate 1, a dielectric layer 3 and a metal nano-cylinder array 4 (a first electrode) are arranged on the modulation layer 2 through photoetching-coating, a second electrode 5 is arranged above the modulation layer 2 which is not covered by the nano-cylinder array above the substrate 1 through coating, and the modulation layer 2 is graphene.
It should be noted that the specific energy band structure causes the surface conductivity σ of the graphene to change greatly when a bias voltage is applied across the graphene, thereby affecting the dielectric constant ∈ of the grapheneg：
In the formula: epsilon0Is a vacuum dielectric constant; omega is angular frequency; t is the thickness of the graphene; the surface conductivity of the graphene obtained by local random phase approximation calculation is about:
in the formula: e represents a elementary charge; k is a radical ofBRepresents the boltzmann constant;
represents the reduced Planck constant; t represents a temperature of 300K; efRepresents the fermi level of graphene; the carrier relaxation time τ is 0.25 ps; scattering ratio of carrier τ-1＝4THz。
Since the aluminum cylinders are designed to be arranged in a two-dimensional array, there is no polarization dependence on incident light, which may be natural light, TE light or TM light. The incident light is vertically incident from bottom to top. Electrodes are manufactured on the surfaces of the graphene and the metal aluminum, so that direct-current bias voltage in the vertical direction can be applied to the graphene to modulate the light intensity of reflected light, and the function of an optical switch is realized.
The performance of the optical switch may be determined by the Modulation Depth (MD) of the light. The dielectric constant of the graphene is changed by applying a direct-current bias voltage to the graphene, so that the light reflectivity of the device is regulated and controlled. When the direct current bias voltage is zero, the absorption of the graphene is remarkably increased due to the remarkable enhancement of the interaction between the graphene and incident light, so that the reflectivity is close to 0 and is expressed as a reflective OFF state; when the direct current bias voltage is larger than zero, the absorption capacity of the graphene to light is weakened, and when the light reflectivity is close to 1, the graphene is in an 'ON' state of reflected light. The modulation depth of the optical switch may be defined as:
it will be appreciated that the dielectric constant around the metallic nanocylinder array 4 changes at different fermi levels of the graphene, thereby affecting the amplitude and frequency of the magnetic plasmon resonance excited by the metallic nanocylinder array 4;
as shown in fig. 1, natural light enters a substrate 1, passes through the substrate 1 and then reaches a modulation layer 2, and reacts with graphene, in a near-infrared band, the graphene serves as a loss medium to absorb electric field energy, the remaining electric field energy continues to propagate to a dielectric layer 3 and a metal nano cylindrical array 4, the metal nano cylindrical array 4 can excite magnetic plasma resonance, the electric field energy is localized in a slit of the metal nano cylindrical array 4, the change of a reflection spectrum under different fermi levels can be understood from the change of the dielectric constant of the graphene along with the change of the fermi levels, and the dielectric constant around the aluminum cylinder changes when the fermi levels of the graphene change due to the fact that the graphene is located below the aluminum cylinder.
It should be noted that the utility model discloses an adopt calculation software FDTD Solutions 2018a, the version number is 8.19.1584 and carry out numerical calculation, and the incident light is the linear polarization light of electric field vibration direction along the x axle. Due to the symmetry of the two-dimensional structure, the linearly polarized light of the electric field vibration direction of the incident light along the y-axis is identical to that along the x-direction, the period P of the aluminum cylinder is 250nm, the diameter D is 200nm, the height H is 190nm, and the number of graphene layers is 15. Figure 3 shows the reflectance and absorbance spectra, respectively, without graphene (other parameters being identical to those with graphene) and with graphene but without applied voltage below the aluminum cylinder. For comparative understanding, FIG. 3(a) also shows the reflectance curve for a uniform aluminum film (30 μm thick) without a structure. As can be seen from fig. 3(a), the reflectance curve with/without graphene has a peak with a lower reflectance at a wavelength of 0.85 μm, which is a change in reflectance due to an intrinsic absorption peak of aluminum. Further comparison of the reflectance with/without graphene shows that: when no graphene exists in the structure, a resonance peak exists when the wavelength is 1.50 mu m, and the reflectivity is 60.98%; in sharp contrast, however, when there is a graphene layer, the reflectance at the 1.54 μm resonance peak suddenly drops to 0.18%, and the absorption of light by the surface structure is greatly increased. To further understand the effect of graphene at the interface on the absorption of the structure, we used FDTD simulation software to calculate the absorption at the interface by placing two transmittance monitors 5nm on both sides of the interface between the aluminum cylinder and the glass (i.e., one monitor on the glass side of the interface and the other monitor on the aluminum cylinder side of the interface). As shown in fig. 3(b), it was found that in the absence of graphene, the absorption at the interface was substantially zero except for the effect of the intrinsic peak of aluminum, and the absorption at this time was mainly due to the intrinsic absorption peak generated by the aluminum cylinder itself. The absorption at the wavelength λ of 1.50 μm is at most 39.02%, due to the resonance absorption produced by the aluminum cylinder exciting the magnetic plasmon resonance. Fig. 3(c) shows the absorption spectrum when graphene is present in the structure, where the absorption of the structure at λ ═ 1.54 μm can reach up to 99.82%. Through the calculation of the two transmittance monitors, the absorptance at the interface between aluminum and glass, that is, the absorptance of graphene, can be obtained. As can be seen from fig. 3(c), at this time, graphene absorption plays a major role in total absorption, and the absorption rate at the wavelength λ of 1.54m can reach 86.61% at the highest, while the absorption rate of aluminum at the wavelength λ of 1.54 μm is only 13.21%, which is reduced by 24.22% compared to the absorption rate at the wavelength λ of 1.54 μm of a bare aluminum cylinder without graphene (37.43%, in fig. 3(b), which indicates that most of the energy has been absorbed by graphene before entering the aluminum cylinder array, and the remaining optical field energy does not reach the absorption limit of the aluminum cylinder, so that the aluminum cylinder array structure with graphene can achieve perfect absorption at the wavelength of 1.54 μm.
Also because as shown in FIG. 4, when the Fermi level increases from 0eV to 0.3eV, the real part of the dielectric constant of graphene increases and the imaginary part decreases, the first-order formant is red-shifted from 1.54 μm to 1.69 μm, and the reflectance slightly increases, increasing from 0.18% to 0.59%; when the fermi level is increased from 0.3eV to 0.5eV, since the real part and the imaginary part of the dielectric constant of graphene are simultaneously decreased, the resonance peak is gradually blue-shifted from 1.69 μm to 1.16 μm, and the reflectance is increased from 0.58% to 55.20%; when the fermi level increases from 0.6eV to 1.0eV, the first order peak disappears completely, the second order peak red-shifts from 1.82 μm to 1.60 μm, and the reflectance decreases from 64.42% to 55.35%, which is due to the further decrease in the real part of graphene, but the imaginary part increases slightly. The change rule of the resonance frequency along with the dielectric constant is consistent with the change rule of magnetic plasma resonance, namely, the frequency of a resonance peak is extremely sensitive to the refractive index of a medium around metal and gradually red-shifts along with the increase of the refractive index of the medium. Based on the huge change of the reflectivity at the resonance peak when graphene exists, the design of the optical switch function can be carried out by utilizing the characteristic and combining the electrical tuning characteristic of the graphene.
Fig. 5(a) is a reflectance graph in which D is fixed to 200nm, H is fixed to 190nm, the number of graphene layers is 15, and when the period P of the aluminum cylinder is increased from 230nm to 270nm and Ef is 0eV, the first-order resonance peak (MP1) gradually undergoes a blue shift, and the reflectance is decreased and then increased; when Ef is 0.5eV, the first-order formant (MP1) also shows a blue-shift tendency, but the reflectance gradually decreases; when Ef is 0.6eV, the first-order formant (MP1) substantially disappears, and the second-order formant (MP2) tends to be red-shifted, and the reflectance gradually increases. When the period P is 250nm, the modulation of reflected light can be realized by adjusting the Fermi level, and the excellent function of the optical switch is realized: when the fermi level Ef is 0eV, the optical switch is in the "OFF" state due to the reflectance close to 0, and when the fermi level Ef is 0.5eV or 0.6eV, the reflectance is close to 0.7, which is in the "ON" state of the optical switch. As can be calculated from equation (3), the modulation depth at the wavelength λ of 1.54 μm is 99.77% at maximum (26.35 dB). When the wavelength increases to 230nm and Ef is 0eV, the first-order resonance peak (MP1) gradually shifts in red, and the reflectance first decreases and then increases; when Ef is 0.5eV, the first-order formant (MP1) also shows a red shift tendency, but the reflectance gradually increases; when Ef is 0.6eV, the second order formant (MP2) tends to blue shift, and the reflectance gradually decreases. The influence of the diameter D of the aluminum cylinder on the frequency and the size of the formants is opposite to the period P, because the change of the diameter D and the period P of the aluminum cylinder enables the width of a medium groove between the aluminum cylinders to change, when the width of the medium groove is larger, the first-order formant resonance effect is stronger, along with the reduction of the width of the groove, the first-order formant (MP1) resonance effect is weakened and gradually red-shifted, and at the moment, the second-order formant (MP2) resonance is strengthened and gradually blue-shifted.
Fig. 5(b) shows reflectance curves for different aluminum cylinder diameters D with a fixed P of 250nm, H of 190nm, 15 graphene layers, and D. When changing the diameter D of the aluminum cylinder, it can be observed that as D increases from 180nm to 230nm, the first-order formant (MP1) gradually red shifts with decreasing reflectance and then increasing reflectance at Ef ═ 0 eV; when Ef is 0.5eV, the first-order formant (MP1) also shows a red shift tendency, but the reflectance gradually increases; when Ef is 0.6eV, the second order formant (MP2) tends to blue shift, and the reflectance gradually decreases. The influence of the diameter D of the aluminum cylinder on the frequency and the size of the formants is opposite to the period P, because the change of the diameter D and the period P of the aluminum cylinder enables the width of a medium groove between the aluminum cylinders to change, when the width of the medium groove is larger, the first-order formant resonance effect is stronger, along with the reduction of the width of the groove, the first-order formant (MP1) resonance effect is weakened and gradually red-shifted, and at the moment, the second-order formant (MP2) resonance is strengthened and gradually blue-shifted.
Fig. 5(c) shows reflectance curves with different aluminum cylinder heights H, with a fixed P of 250nm, D of 200nm, 15 graphene layers. It can be seen that as the height H of the aluminum cylinder increases from 170 nm to 210nm, both the first and second order formants are gradually red-shifted, and the reflectance of the first order formant (MP1) having Ef ═ 0.5eV is gradually increased, the resonance is decreased, and at this time, the resonance absorption of the second order formant (MP2) is increased, and the reflectance is gradually decreased. The reflectance at Ef-0 eV remains substantially unchanged, but the wavelength of the resonance peak is red-shifted from 1.39 μm to 1.66 μm. This characteristic can be used to tune the operating wavelength of the optical switch or to optimize the modulation depth of the optical switch.
In the simulation calculation process, the thickness of the graphene is set to be 15 layers, and actually, the change of the number of layers of the graphene also affects the performance of the device. Fig. 6 is a reflectance chart of the fixed optical switch with different numbers of graphene layers, where P is 250nm, D is 200nm, and H is 190nm, to explore the influence of the number of graphene layers on the device performance. As can be seen from fig. 6, the number of graphene layers has little effect on the frequency of the first-order formant (MP1), and has a smaller effect on the frequency of the second-order formant (MP 2). However, the change of the number of layers of the graphene affects the size of a resonance peak, thereby affecting the modulation depth of the optical switch. As can be seen from fig. 6, when the graphene is increased from 10 layers to 15 layers, the maximum modulation depth at the wavelength λ of 1.54 μm is increased from 94.08% (12.27dB) to 99.77% (26.35dB), and when the number of graphene layers is continuously increased to 20 layers, the maximum modulation depth at the wavelength λ of 1.54 μm is decreased to 99.22% (21.12 dB). Therefore, in this structure, the optimum number of graphene layers is about 15.
In summary, the optimized optical reflection characteristics of the device in the communication band 1400-1700nm are shown in FIG. 7, using 1550nm as the center wavelength in a preferred embodiment of the present invention. The optimized structural parameters are as follows: p is 250nm, D is 200nm, H is 190nm, and the number of graphene layers is 15. As shown in FIG. 7, the reflectivity of the structure is gradually increased and reaches the maximum when the Fermi level is increased from 0eV to 0.6eV and gradually decreases when the Fermi level is increased from 0.6eV to 1.0eV in the 1700nm range of the communication band 1400-, and the reflectivity is gradually decreased. When the fermi level is in the vicinity of Ef 0eV or 0.2eV, the reflectance is close to 0, showing a strong absorption and an "OFF state", and when the fermi level is in the vicinity of 0.6eV, the reflectance may reach 65% or more, showing a strong reflection and an "ON state". The minimum modulation depth of 91.36% (10.63dB) in the whole optical communication range of 1400-1700nm, and the modulation depth of 1544nm can reach 99.77% (25.36dB) at the highest.
The utility model provides a near-infrared broadband light switch based on graphite alkene absorption enhancement utilizes metal aluminium cylinder array can be aroused magnetic plasma resonance effect with the modulation layer 2 and the 4 couplings of metal nanometer cylinder array of graphite alkene, and under magnetic plasma resonance effect condition, graphite alkene is showing the absorption that the reinforcing leads to graphite alkene and is showing the increase with the interact of incident light for the reverberation is showing and is reducing. When the Fermi level of the graphene is changed, the dielectric constant of the graphene is changed, so that the frequency and amplitude of the magnetic resonance effect of the metal aluminum cylindrical array are changed, the function of the optical switch is realized, and the modulation depth of the optical switch is further increased. Because the structure adopts a two-dimensional aluminum cylinder array, the optical switch function of the structure is independent of the polarization state of incident light (no matter whether the incident light is TE, TM light or natural light). Meanwhile, the structure can be realized by combining large-area ultraviolet exposure with metal coating, ion etching on metal is not needed, and the experimental preparation difficulty is greatly reduced.
In light of the foregoing, it is to be understood that various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (10)
1. A near-infrared broadband optical switching device using graphene coupling, comprising: a substrate, and a modulation layer overlying the substrate, characterized in that:
the modulation layer is provided with a dielectric layer and a metal nano-cylinder array through photoetching-coating, the metal nano-cylinder array is used as a first electrode, the modulation layer is provided with a second electrode through coating, the modulation layer is a graphene layer, at least one graphene layer directly grows or is transferred onto the substrate, and the graphene layer is applied with a direct current bias voltage in the vertical direction;
the material of the dielectric layer is photoresist, the photoresist is coated on the modulation layer in a spin coating mode through a spin coating machine to form a uniform photoresist film, and the dielectric layer is formed through a secondary double-beam holographic photoetching process.
2. The graphene-coupled near-infrared broadband optical switch device according to claim 1, wherein: the metal nanometer cylindrical array is made of metal aluminum.
3. The graphene-coupled near-infrared broadband optical switch device according to claim 2, wherein: and uniformly depositing the metal aluminum on the upper surface of the dielectric layer by using a coating process, and completely covering and wrapping the dielectric layer.
4. The graphene-coupled near-infrared broadband optical switch device according to claim 3, wherein: the metal nano-cylinder arrays are arranged in a two-dimensional array.
5. The graphene-coupled near-infrared broadband optical switch device according to claim 1, wherein: the second electrode is deposited over the modulation layer not covered by the nanopillar array.
6. The graphene-coupled near-infrared broadband optical switch device according to claim 5, wherein: the second electrode is made of gold, silver or copper metal.
7. The graphene-coupled near-infrared broadband optical switch device according to claim 6, wherein: the substrate is made of silicon dioxide.
8. The graphene-coupled near-infrared broadband optical switch device according to claim 1, wherein: the modulation depth of the optical switch is defined as:
wherein
And
respectively the reflectivity when the optical switch is open and closed.
9. The graphene-coupled near-infrared broadband optical switch device according to claim 1, wherein: the thickness of the dielectric layer is 190 nm.
10. The graphene-coupled near-infrared broadband optical switch device according to claim 9, wherein: the period of the metal nano cylinder array is 250nm, and the diameter of the metal nano cylinder array is 200 nm.
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