Phase-change material electro-optical modulator based on transparent micro-heater and preparation method of phase-change material electro-optical modulator

Abstract

The invention discloses a phase-change material electro-optical modulator based on a transparent micro heater and a manufacturing method thereof.The device comprises a bottom layer, a supporting layer, an electrode layer and a phase-change layer, the middle area of the substrate layer is suspended, and the electrode layer comprises a transparent electrode layer in the middle area and metal electrode layers arranged on the two sides; the phase change layer covers the space above the transparent electrode layer and is provided with a plurality of phase change material nanometer plates, and a metal cap is arranged above each phase change material nanometer plate. According to the device, voltage is input to the metal electrode layers on the two sides through an external power supply, so that the transparent electrode layers are electrified to generate joule heat, the phase change layer in the space above is driven to perform phase change, the optical dielectric constant of the phase change layer is remarkably changed, and dynamic regulation and control of transmission light in the middle-infrared band are achieved.

Description

Technical Field

[0001] The invention relates to the field of electro-optic modulation, and in particular to a phase-change material electro-optic modulator based on a transparent micro-heater and a manufacturing method thereof. Background Art

[0002] Phase change materials can significantly change their electrical and optical properties by reversibly switching between amorphous and crystalline states, which provides a new idea for designing reconfigurable electro-optical modulators. Among tunable and active materials, phase change materials have unique properties such as non-volatility, CMOS compatibility, scalability, and ultrafast switching. Therefore, combining phase change materials with the structural design of micro-nano photonic devices will greatly improve the performance and device integration of existing electro-optical modulators.

[0003] GST, a compound composed of three elements Ge, Sb and Te in a certain proportion, is a typical thermotropic phase change material. Its characteristics are that any method that can generate high temperature can actually cause the GST phase change, and it can maintain a stable crystalline state after the phase change, and no external energy is required to maintain the phase state of the material. GST has a variety of different element composition ratios, and there are certain differences in properties between them. Among them, Ge2Sb2Te5 has better performance than compounds with other element ratios in terms of phase change speed and ductility, and is the most widely used material in electro-optical modulation devices and phase change material metasurfaces. According to previous literature reports, direct heating, pulsed laser irradiation, and voltage pulses are currently commonly used to regulate the phase state of Ge2Sb2Te5. The advantages and disadvantages of these three methods are obvious, and the application scenarios are different. Directly using equipment such as hot plates for heating is the most direct and convenient, and a large area phase change of the material can be achieved in a short time. However, since the hot plate cannot provide the heat required for rapid annealing in a short time, it is impossible to achieve reversible switching of the phase state of Ge2Sb2Te5 and control of the degree of phase change, and it is difficult to complete the regulation of the phase state of the material in the local area. Compared with direct heating, pulsed laser irradiation has the advantages of fast switching, stable control, reversible switching of materials and control of local phase states, but this method has great limitations in actual application scenarios and requires the construction of large laser equipment and complex optical path systems. The voltage pulse method is the fastest and most convenient. By building a simple electric drive platform and using an external power supply to apply voltage to the electrode layer of the electric drive platform, the electric Joule heat generated when power is applied can arbitrarily switch the phase state of the material. In 2021, Yifei Zhang and others designed a large-scale, electrically reconfigurable, non-volatile metasurface platform based on optical phase change materials. The device uses the optical phase change material Ge2Sb2Se4Te (GSST) to uniquely demonstrate the characteristics of huge non-volatile refractive index modulation capability, broadband low optical loss and large reversible switching volume, which significantly enhances the light-matter interaction in the active optical phase change material medium (see literature: Nature Nanotechnology 2021, 661, 666.); In 2022, Sajjad et al. proposed to use the difference in optical properties before and after the phase change of GST-225 to design an in-situ electrically driven tunable metasurface to achieve non-volatile, reversible, multi-level, fast and significant optical modulation in the near-infrared spectrum. The electrically driven reconfigurable metasurface has an efficiency of 80% and has a quasi-continuous spectral tuning capability of more than 250nm (see literature: Nature Communications 2022, 13, 1696.). However, both of the above will have filamentation during the power-on process, that is, the thin wires formed by the first crystallization will prevent the crystallization of the material in the surrounding area, thereby affecting the uniform crystallization of the entire area.The "filament effect" prevents the current in the electro-optical modulator from switching the phase directly through the phase change material, thus affecting the performance of the device. In order to solve the problem of the "filament effect", the application of microheaters to the electric drive platform can further overcome the filamentation phenomenon generated during the power-on process of the phase change material. However, traditional microheaters usually use highly reflective metals as thermal resistor layers, which results in the phase change material optical modulator integrated with the microheater being limited to work in the reflection mode in the mid-infrared to terahertz band. In addition, the power consumption generated by the voltage pulse is high, and most of the heat of the microheater will be dissipated to the substrate, which further hinders the integration of the phase change material optical modulator with the reconfigurable micro-optical chip system. The prior art consists of a substrate layer and a covering layer to form a device, and there is a space between the covering layer and the substrate layer, and a number of gold nanodisks are arranged in the space, and each gold nanodisk is provided with a phase change material. The covering layer covers the phase change material as the light field control unit of the device, and metal electrodes are arranged on both sides of the covering layer as the electrode control unit of the device. By applying voltage externally, the covering layer continuously generates Joule heat to drive the phase change material to undergo a phase change, causing its optical dielectric constant to change significantly, thereby achieving dynamic electro-optical modulation of mid-infrared light. The device uses a two-dimensional semi-metallic material PtSe2 as the covering layer. Although it has the advantages of high light transmittance, good conductivity, a maximum modulation depth of about 64.8% for reflected light, and the ability to dynamically control spatial incident light, it still has problems such as low modulation depth for transmitted light, uneven heating, and high heat loss. Summary of the invention

[0004] The present invention aims to overcome the problems of low modulation depth of transmitted light, uneven heating and high heat loss of electro-optical modulation devices in the prior art, and provides a phase change material electro-optical modulation device based on a transparent microheater and a manufacturing method thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A phase change material electro-optical modulation device based on a transparent microheater comprises a substrate layer, a support layer, an electrode layer and a phase change layer; a through hole is provided in the middle of the substrate layer; the support layer is located on the upper surface of the substrate layer; the electrode layer is located on the upper surface of the support layer, comprising a transparent electrode and metal electrodes at both ends of the transparent electrode; the phase change layer is located on the upper surface of the transparent electrode; a metal cap is provided on the upper surface of the phase change layer; and a metal layer is provided on the upper surface of the transparent electrode.

[0006] In the present invention, the substrate layer is a silicon layer, a through hole is provided in the middle thereof, and the support layer is located on the upper surface of the substrate layer, covering the through hole; the support layer includes a silicon nitride layer and a silicon oxide layer, which are transparent in the ultraviolet to far infrared bands, can withstand high-intensity stress, play a good supporting role, and can balance the stress generated during the heating process of silicon nitride. Preferably, the upper surface area of ​​the through hole is 0.3 to 0.4% of the upper surface area of ​​the substrate layer, for example, the upper surface area of ​​the through hole is 600×600μm, and the upper surface area of ​​the substrate layer is 10×10mm; the thickness of the silicon nitride layer is 200nm, and the thickness of the silicon oxide layer is 300nm; the silicon oxide layer is located on the upper surface of the silicon nitride layer.

[0007] In the present invention, the transparent electrode layer is a transparent conductive oxide film layer, preferably an ITO film layer; the thickness of the transparent electrode layer is 300nm, the upper surface area of ​​the transparent electrode layer is 2-3% of the upper surface area of ​​the through hole, and the transparent electrode is entirely above the through hole.

[0008] In the present invention, the material of the phase change layer is Ge2Sb2Te5, and the phase change layer is a phase change material nanodisk array structure. Preferably, the shape of the phase change material nanodisk is cylindrical, with a diameter of 260nm, a height of 100-200nm, and a spacing between the phase change material nanodisks of 200-300nm. By designing the structural parameters of the phase change material nanodisks, the optimal modulation capability of spatial light can be obtained.

[0009] In the present invention, the metal electrode is a gold electrode; the metal cap is a gold cap; and the metal layer is a gold layer. Preferably, the metal cap has the same shape as the phase change material nanodisk, the same diameter as the phase change material nanodisk, and the same thickness as the gold electrode layer and the metal layer. The metal cap is deposited together with the gold electrode layer and the metal layer through a designed shadow mask and attached directly above the phase change material nanodisk, thereby enhancing the interaction between the spatial light and the phase change material and generating a stronger local resonance.

[0010] The present invention discloses a method for preparing a phase change material electro-optical modulation device based on a transparent micro-heater, comprising the following steps: (1) preparing a support layer on the substrate layer, and then opening a through hole in the middle of the substrate layer; (2) preparing a transparent electrode layer on the support layer; and then preparing a phase change layer on the transparent electrode layer; (3) Preparing a metal film on the support layer, the transparent electrode layer and the phase change layer to form a metal electrode, a metal cap and a metal layer.

[0011] In the present invention, the support layer is prepared by electron beam evaporation. Preferably, a silicon nitride film of the support layer is prepared on the substrate layer by electron beam evaporation, and then a transparent window is etched in the central area of ​​the substrate by wet etching (i.e., a through hole is prepared under the silicon nitride film), and then a silicon oxide film is prepared on the silicon nitride film by electron beam evaporation.

[0012] In the present invention, the transparent electrode layer is prepared by ion beam sputtering deposition; the phase change layer is prepared by ion beam sputtering deposition; and the metal film is prepared by electron beam evaporation to form a metal electrode, a metal cap and a metal layer.

[0013] The phase change material electro-optical modulation device based on the transparent microheater of the present invention has high thermal conductivity, better temperature uniformity, is transparent in the near-infrared to mid-infrared band, has the characteristics of good conductivity, high light transmittance, high melting point and easy preparation, can exist stably in the environment for a long time, improves the heating stability, and reduces the loss of incident light; it also has the characteristics of high conductivity, good stability and not easy to oxidize, can reduce the input voltage of the device and improve the stability of the device.

[0014] The invention discloses a method for manufacturing a phase change material electro-optical modulation device based on a transparent microheater, which is suitable for manufacturing a phase change material electro-optical modulation device based on a transparent microheater. The device is composed of a multi-layer composite structure including a substrate layer, a support layer, an electrode layer and a phase change layer. A mid-infrared electro-optical modulation device having a suspended transparent MEMS microheater in the middle region and an ITO / Ge2Sb2Te5 / Au three-layer stacked structure is prepared. Incident light interacts with a Ge2Sb2Te5 nanodisk to form a plasmon resonance. The metal cap at the top further enhances the local resonance. Voltage is input through the gold electrodes on both sides to cause the high-impedance transparent electrode ITO in the central region to generate Joule heat, thereby inducing a phase change of the phase change material nanodisk array above, resulting in a significant change in its optical dielectric constant, thereby dynamically electro-optically regulating the transmitted light switching state of the device.

[0015] Therefore, the present invention has the following beneficial effects: the device of the present invention adopts a wet etching method to prepare a suspended thin film microheater, which has the characteristics of high heating efficiency, fast response time and good mechanical stability; the ITO electrode is transparent in the mid-infrared band, which reduces the loss of incident light, and the high impedance can generate higher heat during the heating process; the present invention adjusts the phase state of the phase change material nanodisk by voltage, which can not only make it quickly and reversibly switch between the amorphous state and the crystalline state, but also can dynamically regulate the switching state of the incident light in the mid-infrared band. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional view of a structural unit of the phase change material electro-optic modulation device of the present invention.

[0017] Figure 2 It is a top view of the structural unit of the phase change material electro-optic modulation device of the present invention.

[0018] Figure 3 It is a top view of the Ge2Sb2Te5 nano disk array of the phase change material electro-optic modulation device of the present invention.

[0019] Figure 4 It is a phase change schematic diagram of the phase change material electro-optic modulation device of the present invention.

[0020] Figure 5 It is a schematic diagram of the temperature distribution of the simulated phase change material electro-optic modulation device of the present invention when a 2V voltage is input for 100µs.

[0021] Figure 6 It is a production flow chart of the phase change material electro-optic modulation device of the present invention.

[0022] Figure 7 It is a transmission spectrum diagram of the simulated phase change material electro-optic modulation device of the present invention in the crystalline and amorphous mid-infrared wavelength range.

[0023] Figure 8 This is the reflection spectrum of the simulated phase change material electro-optic modulation device of the present invention in the crystalline and amorphous mid-infrared wavelength range Fig. 9 The transmission spectra of the simulated phase change material electro-optic modulation device of the present invention in the crystalline and amorphous states in the mid-infrared wavelength range using different phase change material nanodisk heights are compared. Fig.10 It is a comparison diagram of modulation depths in the mid-infrared wavelength range of the crystalline and amorphous states of the simulated phase change material electro-optic modulation device of the present invention using different phase change material nanodisk heights; In the figure: 1. substrate; 2. support layer; 3. transparent electrode layer; 4. gold electrode layer; 5. phase change material nanodisk; 6. metal cap; 11. metal layer; 12. through hole; a. amorphous state; c. crystalline state. DETAILED DESCRIPTION

[0024] The present invention discloses a phase change material electro-optic modulation device based on a transparent micro-heater, which uses a micro-heater to induce phase change of a phase change material for electro-optic modulation; the electro-optic modulation device includes a substrate layer, a support layer, an electrode layer and a phase change layer; the substrate layer is made of silicon, the middle region of the substrate layer is suspended (through hole), the support layer is made of silicon nitride and silicon oxide, the electrode layer includes a transparent electrode layer and metal electrode layers provided on both sides, the phase change layer covers the space above the transparent electrode layer, and is provided with a plurality of phase change material nano-disks, each of which is provided with a metal cap above the phase change material nano-disk, and a metal layer is provided on the upper surface of the transparent electrode layer, that is, the metal layer and the phase change layer jointly cover the upper surface of the transparent electrode. Among them, the electrode layer serves as the electrode and light field control unit of the device, and an external power supply inputs voltage to the metal electrode layers on both sides, so that the transparent electrode layer is energized to generate Joule heat, driving the phase change layer in the upper space to change phase, so that its optical dielectric constant changes significantly, thereby realizing dynamic control of the transmitted light in the mid-infrared band.

[0025] The present invention manufactures a suspended film heater on a substrate, which has the advantages of high heating efficiency, low heat loss, fast response time, etc. The suspended film design improves the heating efficiency of the micro heater and enables it to work in a transmission mode.

[0026] In the present invention, the thickness of the substrate layer silicon is 400µm, the length and width are 10×10mm, the suspended area is prepared by back wet etching method, the thickness is 400µm, the length and width are 600×600µm, and it is a through-hole structure. The thickness of the supporting layer silicon nitride is 200nm, and the thickness of silicon oxide is 300nm. It is transparent in the ultraviolet to far infrared band, can withstand high-intensity stress, play a good supporting role, and can balance the stress generated during the heating process of silicon nitride.

[0027] In the present invention, the material of the transparent electrode layer is a transparent conductive oxide film ITO, the thickness of the transparent electrode layer is 300nm, and the length and width are 100×100µm; the material of the phase change layer is Ge2Sb2Te5, and the phase change layer is provided with a plurality of phase change material nanodisks, the shape of the phase change material nanodisks is circular, the diameter is 260nm, and the height is 100-200nm. The spacing of the phase change material nanodisks is 200-300nm, and the best modulation capability of spatial light can be obtained by optimizing the structural parameters of the phase change material nanodisks; the material of the metal layer is gold, the material of the metal electrode layer is gold, and the material of the metal cap is gold, the shape of the metal cap is the same as that of the phase change material nanodisk, the diameter of the metal cap is the same as that of the phase change material nanodisk, and the thickness is the same as that of the gold electrode layer and the metal layer, and the metal cap is deposited together with the gold electrode layer through a designed shadow mask and attached to the top of the phase change material nanodisk, so as to enhance the interaction between the spatial light and the phase change material and generate stronger local resonance.

[0028] The present invention discloses a method for preparing the above-mentioned phase change material electro-optical modulation device based on a transparent microheater, comprising the following steps: (1) Preparing a supporting layer silicon nitride film on the substrate layer by electron beam evaporation; (2) etching a transparent window in the central area of ​​the back of the substrate by wet etching; (3) Preparation of silicon oxide film on silicon nitride film by electron beam evaporation; (4) Depositing a transparent electrode layer with a lateral size of 100 × 100 µm using a shadow mask and ion beam sputtering; (5) Spin-coat ZEP photoresist on the transparent electrode layer using a coating machine; (6) Expose the pattern by electron beam and develop it; (7) Depositing the phase change material Ge2Sb2Te5 on top of the ZEP photoresist by ion beam sputtering, and then removing the residual photoresist by stripping technology to obtain the Ge2Sb2Te5 nanodisk array; (8) Use shadow mask and electron beam evaporation to deposit gold electrodes, metal caps above the Ge2Sb2Te5 nanodisk arrays, and metal layers between the nanodisk arrays.

[0029] The prior art discloses an electro-optical modulation device based on a micro electric heater and a manufacturing method thereof. The device is composed of a substrate layer and a covering layer. There is a space between the covering layer and the substrate layer. A plurality of gold nanodisks are arranged in the space, and each gold nanodisk is provided with a phase change material. The covering layer covers the phase change material and serves as the light field control unit of the device. Metal electrodes are arranged on both sides of the covering layer as the electrode control unit of the device. The device uses a two-dimensional semi-metal material PtSe2 as a covering layer. Although it has the advantages of high light transmittance, good conductivity, and a maximum modulation depth of about 64.8% for reflected light, and can realize dynamic control of spatial incident light, it still has the problem that the transmitted light cannot be modulated and the filamentation phenomenon can only be reduced by adjusting the device structure and size. The device of the present invention regulates the phase change material device by adopting a micro heater with a central opening, which can achieve a maximum modulation depth of about 71.6% for the transmitted light, and can concentrate the generated electric joule heat on the support layer above the through hole when the power is turned on, which increases the stability and uniformity of the heating, which makes the phase change material crystallize more uniformly during the phase change process, thereby reducing the filamentation phenomenon.

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. The raw materials used in the present invention are all existing products, and the specific preparation operations and performance tests are all conventional techniques. Embodiment 1

[0031] See also Figure 1As shown, it is a structural cross-sectional view of a phase change material electro-optical modulation device based on a transparent microheater, including a substrate layer 1, a support layer 2, a transparent electrode layer 3, a gold electrode layer 4 and a phase change layer 5. The material of the substrate layer 1 is silicon, with a thickness of 400µm, a length and a width of 10×10mm, and the silicon on the back of the central area is etched away by wet etching to form a through-hole structure 12 (with a thickness of 400µm, a length and a width of 600×600µm), so that the support layer 2 above the central area of ​​the substrate layer 1 is suspended; the material of the support layer 2 is silicon nitride and silicon oxide, with a silicon nitride thickness of 200nm and a silicon oxide thickness of 300nm; the material of the transparent electrode layer 3 is ITO, located directly above the central area of ​​the support layer 2, with a thickness of 300nm, a length and a width of 100×100µm, and the transparent electrode layer 3 is on both sides. A gold electrode layer 4 having a thickness of 100 nm; a plurality of phase change material nanodisks 5 and a metal layer 11 are arranged above the transparent electrode layer 3; the phase change material nanodisks 5 are circular in shape and made of phase change material Ge2Sb2Te5; all phase change material nanodisks 5 form a Ge2Sb2Te5 nanocolumn array; the diameter of the phase change material nanodisk 5 is 260 nm, the height is 150 nm, and the spacing between the nanodisks is 200 nm; the shape of the metal cap 6 is the same as that of the phase change material nanodisk 5, covering the phase change material nanodisk 5 directly above, and having a thickness of 100 nm; the metal film between the nanodisk arrays forms a metal layer.

[0032] See also Figure 2 As shown, it is a top view of the structure of the phase change material electro-optical modulation device based on the transparent microheater, the supporting layer is entirely covered on the substrate, in order to distinguish the supporting layer from the substrate, it refers to the supporting layer above the through hole; wherein the transparent electrode 3 is obtained by shadow mask and ion beam sputtering, and covers the central area of ​​the supporting layer 2; the gold electrode layer 4 is obtained by shadow mask and electron beam evaporation, and is arranged on both sides of the transparent electrode layer 3 and above the substrate layer 1 and the supporting layer 2, specifically, it is a conventional technology, and it can be powered on; a gold layer is provided at the interval of the nano disk array, and the structural size and arrangement of the transparent electrode layer 3 and the gold layer can achieve the best impedance matching, enhance the electric Joule heat generated inside the device when powered on, and has the characteristics of low heating loss, high efficiency and good stability, and can concentrate the heat on the transparent electrode layer 3 and further improve the stability and temperature of the device heating; a voltage is input to the gold electrode layer 4 by an external power supply, so that the transparent electrode layer 3 is powered on to generate Joule heat, drive the Ge2Sb2Te5 nano disk array to phase change, and significantly change its optical dielectric constant.

[0033] See also Figure 3As shown, a top view of a Ge2Sb2Te5 nanodisk array of a phase change material electro-optical modulation device based on a transparent microheater is shown. The Ge2Sb2Te5 nanodisk array is composed of all phase change material nanodisks 5, which are located directly above the transparent electrode layer 3 and are obtained by electron beam exposure, ion beam sputtering and stripping technology.

[0034] See also Figure 4 As shown, it is a schematic diagram of the phase change of the phase change material electro-optical modulation device based on the transparent microheater. By applying voltage to the gold electrode layer 4 externally, since the impedance of the transparent electrode layer 3 is much higher than that of the gold electrode layer 4, the electric Joule heat generated when power is turned on is concentrated on the transparent electrode layer 3, causing the phase change material nanodisk 5 above it to change phase and the optical dielectric constant to change significantly, thereby realizing dynamic regulation of the incident mid-infrared light in space.

[0035] See also Figure 5 As shown in the figure, the temperature distribution diagram of the transparent micro-heater when the external voltage of 2V is input is obtained by electrothermal simulation calculation using finite element multi-physics field analysis method (COMSOL). From the results of electrothermal simulation calculation, the suspended film design reduces the diffusion of heat to the substrate. The temperature of the transparent electrode layer 3 in the central area reaches an average of 600K when the power is applied for 100us, which is far higher than the phase transition temperature of Ge2Sb2Te5.

[0036] See also Figure 6 As shown, the specific steps for making a phase change material electro-optical modulation device based on a transparent microheater are as follows: (1) Preparing a supporting layer silicon nitride film on the substrate layer by electron beam evaporation; (2) etching a transparent window in the central area of ​​the back of the substrate by wet etching; (3) Preparation of silicon oxide film on silicon nitride film by electron beam evaporation; (4) Depositing a transparent electrode layer with a lateral size of 100 × 100 µm using a shadow mask and ion beam sputtering; (5) Spin-coat ZEP photoresist on the transparent electrode layer using a coating machine at a speed of 3000 r / min and a coating temperature of 120°C; (6) Expose the pattern by electron beam and develop it; (7) Depositing the phase change material Ge2Sb2Te5 on top of the ZEP photoresist by ion beam sputtering, and then removing the residual photoresist by stripping technology to obtain the Ge2Sb2Te5 nanodisk array; (8) Use shadow mask and electron beam evaporation to deposit gold electrodes, metal caps above the Ge2Sb2Te5 nanodisk arrays, and metal layers between the nanodisk arrays.

[0037] See also Figure 7 and Figure 8 As shown in the figure, the transmission spectrum and reflection spectrum of Ge2Sb2Te5 in the mid-infrared wavelength range before and after the phase change are obtained by simulation calculation using the finite difference time domain method (FDTD). After optimizing the structural size, the best impedance matching can be achieved, and the resonance peak generated when the local electric field resonates inside the device is enhanced. By applying an external voltage to the electrode, Ge2Sb2Te5 phase changes and changes its optical dielectric constant, so that it can actively tune the resonance wavelength of the transmitted light. The simulation calculation results show that when Ge2Sb2Te5 is in a completely amorphous state, the maximum transmission peak is reached at a wavelength of 2.26µm, and the transmittance is 71.63%. When Ge2Sb2Te5 is in a completely crystalline state, the extinction coefficient K increases significantly, which is equivalent to a metal. At a wavelength of 2.26µm, the transmittance is close to 0, and the light transmission is almost blocked. The maximum modulation depth is 71.60%. At this time, the transmittance peak red-shifts to a wavelength of 3.41µm, and the transmittance drops to 10.54%. From the red shift of the transmission peak before and after the phase change, it can be seen that the effective dielectric constant caused by the phase change changes significantly, the resonance peak value decreases significantly, and the resonance wavelength shifts significantly.

[0038] Referring to the above preparation method, different devices were obtained by changing the parameters of the phase change material nanodisk (height 100-200nm). Fig. 9 and Fig.10 As shown in the figure, the transmission spectra and modulation depth comparison of Ge2Sb2Te5 crystalline and amorphous states in the mid-infrared wavelength range with different phase change material nanodisk heights are compared. As the phase change material nanodisk height increases from 100nm to 200nm, the maximum modulation depth increases from 26.76% to 71.60%, the resonance wavelength undergoes a significant blue shift, and there is a significant difference in the modulation depth. Although the increase in the height of the phase change material nanodisk will increase the difficulty of peeling during the preparation process, it will enhance the plasmon resonance formed by the incident light and the phase change material nanodisk, and further increase the switching amplitude of the transmitted light.

[0039] The invention discloses a mid-infrared electro-optical modulation device based on a transparent micro-heater and a manufacturing method thereof. The device consists of a multi-layer composite structure including a silicon substrate, a silicon nitride and silicon oxide support layer, an ITO transparent electrode layer, a gold electrode layer, a phase change material nano-disk array, a gold cap, etc. A mid-infrared electro-optical modulation device with a suspended transparent micro-heater in the central region and an ITO / Ge2Sb2Te5 / Au three-layer stacking structure is prepared. The suspended film-type design can reduce the diffusion of heat to the substrate and improve the heating stability. The incident light interacts with the Ge2Sb2Te5 nano-disk to form a plasmon resonance. The metal cap at the top further enhances the local surface plasma resonance. Voltage is input through the gold electrode layers on both sides, so that the high-impedance transparent electrode layer in the central region generates Joule heat, which triggers the phase change of the phase change material nano-disk above to significantly change its optical dielectric constant, thereby dynamically electro-optically regulating the transmitted light switch state of the device. The present invention prepares a micro heater suspended in the center area by a back wet etching method, which greatly reduces the diffusion of heat to the substrate area; by optimizing the volume and arrangement of transparent electrodes and metal electrodes, the stability and uniformity of heating are improved, so that the Ge2Sb2Te5 nanodisk array undergoes a more uniform and stable phase change when powered on, almost avoiding the occurrence of filamentation. The device involved in the present invention can operate in the mid-infrared band of 2-5um. When the height of the Ge2Sb2Te5 nanodisk array is 200nm, at a wavelength of 2.26um, the transmittance of Ge2Sb2Te5 in the amorphous state reaches 71.63%, and the transmittance in the crystalline state is close to 0. The maximum modulation depth of the transmitted light can reach 71.6%, and the extinction ratio reaches 204, realizing the dynamic regulation of the switching state of the incident light in the mid-infrared band.

[0040] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0041] Although the terms such as phase change layer, support layer, cover layer and metal cap are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. A phase change material electro-optical modulation device based on a transparent microheater, comprising a substrate layer, a support layer, an electrode layer and a phase change layer; a through hole is provided in the middle of the substrate layer; the support layer is located on the upper surface of the substrate layer; the electrode layer is located on the upper surface of the support layer, comprising a transparent electrode and metal electrodes at both ends of the transparent electrode; the phase change layer is located on the upper surface of the transparent electrode; a metal cap is provided on the upper surface of the phase change layer; and a metal layer is provided on the upper surface of the transparent electrode.

2. The phase change material electro-optical modulation device based on the transparent micro-heater according to claim 1, characterized in that: The substrate layer is a silicon layer; the supporting layer includes a silicon nitride layer and a silicon oxide layer; and the transparent electrodes are all above the through holes.

3. The phase change material electro-optical modulation device based on the transparent micro-heater according to claim 1, characterized in that: The transparent electrode layer is a transparent conductive oxide thin film layer; the material of the phase change layer is Ge2Sb2Te5; and the phase change layer is a phase change material nano disk array structure.

4. The phase change material electro-optical modulation device based on the transparent micro-heater according to claim 3, characterized in that: In the phase change material nano disk array structure, the phase change material nano disk is cylindrical in shape, has a height of 100-200 nm, and a spacing between the phase change material nano disks is 200-300 nm.

5. The phase change material electro-optical modulation device based on a transparent micro-heater according to claim 1, characterized in that: The metal electrode is a gold electrode; the metal cap is a gold cap; and the metal layer is a gold layer.

6. The method for preparing the phase change material electro-optical modulation device based on the transparent micro-heater according to claim 1 comprises the following steps: (1) preparing a support layer on the substrate layer, and then opening a through hole in the middle of the substrate layer; (2) preparing a transparent electrode layer on the support layer; and then preparing a phase change layer on the transparent electrode layer; (3) Preparing a metal film on the support layer, the transparent electrode layer and the phase change layer to form a metal electrode, a metal cap and a metal layer.

7. The method for preparing a phase change material electro-optical modulation device based on a transparent micro-heater according to claim 6, characterized in that: The supporting layer is prepared by electron beam evaporation; the transparent electrode layer is prepared by ion beam sputtering deposition; the phase change layer is prepared by ion beam sputtering deposition; the metal film is prepared by electron beam evaporation to form a metal electrode, a metal cap and a metal layer.

8. The method for preparing a phase change material electro-optical modulation device based on a transparent microheater according to claim 6, characterized in that: A supporting layer silicon nitride film is prepared on the substrate layer by electron beam evaporation, a transparent window is etched in the central area of ​​the substrate by wet etching, and then a silicon oxide film is prepared on the silicon nitride film by electron beam evaporation.

9. Use of the phase change material electro-optical modulation device based on the transparent microheater as claimed in claim 1 in the preparation of an optical modulation device.

10. The electro-optical control method of the phase change material electro-optical modulation device based on the transparent micro-heater according to claim 1, characterized in that: By inputting voltage through the electrode layer, the transparent electrode generates Joule heat, which triggers the phase change of the phase change layer above, causing its optical dielectric constant to change, thereby dynamically electro-optically controlling the transmitted light switching state of the device.

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