Light and microwave bidirectional signal conversion metasurface and communication system based on metasurface

Abstract

The invention discloses a light and microwave bidirectional signal conversion metasurface and a communication system based on the metasurface, the metasurface comprises a metasurface unit array, a first feeder network and a second feeder network, each metasurface unit comprises a dielectric substrate, and a front resonant structure and a back resonant structure respectively located on the front side and the back side of the dielectric substrate; the front resonance structures arranged in the same row in the x direction in the array are connected in series, and the front resonance structures arranged in different rows in the y direction are connected in parallel through a first feeder network; the back resonance structures arranged in the same row in the x direction in the array are connected in series, and the back resonance structures arranged in different rows in the y direction are connected in parallel through a second feeder network; when microwaves polarized in the x direction irradiate the front face of the metasurface, forward conversion from a microwave signal to an optical signal is achieved; when microwaves polarized in the y direction irradiate the front face of the metasurface, reverse conversion from an optical signal to a microwave signal is achieved. According to the invention, bidirectional signal conversion between light and microwave is realized.

Description

Technical Field

[0001] The present invention relates to the field of optical microwave technology, and in particular to an optical and microwave bidirectional signal conversion metasurface and a communication system based on the metasurface. Background Art

[0002] The mutual conversion of energy and information between light and microwaves has important application prospects in modern electronic communications and quantum physics. The exchange platform of light and microwaves can not only connect the microwave domain and the optical domain, but also make full use of the advantages of microwaves and light waves in different propagation media to achieve seamless cross-media transmission. It is a very promising solution for realizing the integrated information network of air, space, land and sea in the future. Due to the huge frequency span of light and microwaves, efficient interaction between light and microwaves is facing severe challenges. In recent years, the conversion of microwaves to light waves has been achieved using methods such as optical fiber technology, plasma cavity, nonlinear materials, and nanomechanical coupling. However, many verified schemes are based on optical fiber and circuit technology, and require external power supplies to perform multiple intermediate processes, which undoubtedly increases the cost, power consumption and system complexity, greatly limiting its wireless application in free space. In addition, these conversion devices are difficult to further develop to achieve the reverse process from light to microwave, so there are many limitations.

[0003] A metasurface is a two-dimensional structure composed of artificially designed subwavelength units that can control wave properties in free space with high resolution. By designing the unit structure, many different functions have been realized on the metasurface. Microwaves can be used to collect radio frequency energy and light waves can be used to manipulate the propagation characteristics of microwaves. This has laid a new research direction for designing energy and information conversion platforms between light and microwaves. In recent years, many metasurface structures based on the interaction between light waves and microwaves have been proposed for information transmission. However, it is difficult for the metasurfaces currently studied to achieve bidirectional conversion of light and microwaves at the same time without relying on external power supplies. Therefore, how to use metasurfaces to build a bidirectional conversion platform for light and microwaves that does not rely on external power supplies for energy and signal conversion remains a difficult problem. Summary of the invention

[0004] Purpose of the invention: One purpose of the present invention is to provide a light and microwave bidirectional signal conversion metasurface, which realizes the bidirectional conversion of light and microwave by integrating Schottky diodes and photodiodes on the metasurface unit structure, and can control the reflection phase of the incident microwave by light intensity.

[0005] Another object of the present invention is to provide a communication system based on the above-mentioned metasurface.

[0006] Technical solution: The optical and microwave bidirectional signal conversion metasurface described in the present invention comprises m×n double-sided metasurface units arranged in an array, a first feeder network and a second feeder network, wherein the double-sided metasurface units comprise a dielectric substrate, and a front resonant structure and a back resonant structure respectively located on the front and back sides of the dielectric substrate; the front resonant structures arranged in the same row along the x direction in the array are connected in series, and the front resonant structures arranged in different rows along the y direction are connected in parallel through a first feeder network and then connected to both ends of a laser diode; the back resonant structures arranged in the same row along the x direction in the array are connected in series, and the back resonant structures arranged in different rows along the y direction are connected in parallel through a second feeder network;

[0007] When microwaves polarized along the x-direction irradiate the front side of the metasurface, the microwaves will be effectively absorbed by the front resonant structure and rectified into DC energy to drive the laser diode to emit light, thereby realizing the forward conversion of microwave signals to optical signals. When microwaves polarized along the y-direction irradiate the front side of the metasurface, the microwaves will pass through the front resonant structure and the dielectric substrate and reach the back resonant structure. By adjusting the light intensity of the photodiode loaded on the back resonant structure, the reflection amplitude of the incident microwave can be flexibly controlled, and the reverse conversion of optical signals to microwave signals can be realized.

[0008] Preferably, the front resonant structure includes three sections of metal strips arranged along the x-axis direction, the first and second sections of the metal strips are connected by a Schottky diode, and the second and third sections of the metal strips are connected by an inductor; after the metal strips of adjacent double-sided metasurface units in the x-direction in the array are connected in series, the two ends are respectively connected to the first metal strip and the second metal strip of the first feeder network.

[0009] Preferably, the back side resonant structure includes two spaced-apart metal sheets and a photodiode loaded between the two spaced-apart metal sheets, the upper row of metal sheets of adjacent double-sided metasurface units in the x-direction in the array are connected in series to the third metal strip of the second feeder network, and the lower row of metal sheets are connected in series to the fourth metal strip of the second feeder network, so that all the photodiodes are connected in parallel.

[0010] Preferably, the back side resonance structure further comprises a resistor, and the resistor is connected in parallel with the photodiode and loaded between two spaced metal sheets to construct a charge and discharge circuit.

[0011] Preferably, the two spaced-apart metal sheets are two identical metal copper sheets.

[0012] Preferably, the first feeder network includes a first metal strip, a second metal strip, a first feeder and a second feeder, the first metal strip and the second metal strip are arranged on the front side of the dielectric substrate, the first feeder and the second feeder are arranged on the back side of the dielectric substrate, the first metal strip and the second metal strip are connected to the first feeder and the second feeder through two metal through holes, respectively, and the first feeder and the second feeder are connected to the positive and negative electrodes of the laser diode, respectively.

[0013] Preferably, the second feeder network includes a third metal strip and a fourth metal strip, and the third metal strip and the fourth metal strip are arranged on the back side of the dielectric substrate.

[0014] Preferably, the relative dielectric constant of the dielectric substrate material is 2.65, the loss tangent is 0.001, and the thickness is 2.0 mm.

[0015] A communication system constructed based on the optical and microwave bidirectional signal conversion metasurface includes: an optical and microwave bidirectional signal conversion metasurface, a microwave end transmitter and a microwave end transceiver located on the front side of the metasurface, and a laser end receiver and a laser end transmitter located on the back side of the metasurface;

[0016] In the forward conversion transmission link from microwave signals to optical signals, the signal to be transmitted is encoded onto the BASK microwave signal through the microwave end transmitter to drive and modulate the metasurface, thereby rectifying and generating a green OOK laser signal. The generated OOK laser signal is further demodulated into a digital baseband signal through the laser end receiver, and finally the signal to be transmitted is restored;

[0017] In the reverse conversion transmission link from optical signal to microwave signal, the signal to be transmitted is first converted into a data bit stream, encoded onto an underwater green OOK laser signal by the laser-end transmitter, and irradiated with the photodiode on the back of the metasurface; subsequently, the reflection amplitude response of the metasurface is rapidly changed; at this time, when the microwave-end transceiver transmits y-polarized microwaves to the front of the metasurface, the reflected BASK microwave signal is received by the microwave-end transceiver and demodulated into a digital baseband signal through the software-defined radio platform, thereby restoring the video content.

[0018] Furthermore, the optical and microwave bidirectional signal conversion metasurface, microwave transmitter and microwave transceiver are located in the air, and the laser receiver and laser transmitter are located in the water, thereby achieving bidirectional full-duplex capability across the two media of air and water.

[0019] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are: integrating Schottky diodes and photodiodes on double-sided metasurface units, realizing bidirectional conversion of optical signals and microwave signals, and being able to reversely regulate the reflection amplitude of incident microwaves through the intensity of optical signals. In addition, the metasurface composed of the metasurface units can be used to construct a bidirectional communication system based on laser OOK and microwave BASK modulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a front schematic diagram of the super surface of the present invention;

[0021] Figure 2 is a schematic diagram of the back side of the super surface of the present invention;

[0022] Figure 3 Schematic diagram of the overall structure of the super surface of the present invention;

[0023] Figure 4 This is a schematic diagram of the structure of the super surface unit of the present invention;

[0024] Figure 5 A schematic diagram of a back-surface resonance structure of a metasurface unit structure in one embodiment of the present invention;

[0025] Figure 6 It is a reflection amplitude diagram obtained by simulating the metasurface unit structure of the present invention in different working modes;

[0026] Figure 7 is the green laser power output measured at different incident microwave powers;

[0027] Figure 8 is the microwave reflection amplitude measured under green laser irradiation of different powers;

[0028] Fig. 9 It is the principle diagram of the two-way hybrid communication system of the present invention;

[0029] In the figure: 1. dielectric substrate; 2. front resonant structure; 3. back resonant structure; 21. metal strip; 22. Schottky diode; 23. inductor; 31. metal sheet; 32. photodiode; 33. resistor; 41. first metal strip; 42. second metal strip; 43. first feed line; 44. second feed line; 51. third metal strip; 52. fourth metal strip; 6. laser diode. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0031] Previous optical-to-microwave conversion platforms were mostly based on optical fiber and circuit technology, and required external power to perform multiple intermediate processes, which increased cost, power consumption and system complexity, greatly limiting their wireless applications in free space. In addition, these conversion devices are difficult to further develop to achieve the reverse process from light to microwave, so there are many limitations.

[0032] Based on the above problems, the present invention provides a light and microwave bidirectional signal conversion metasurface. First, a double-sided metasurface unit is designed. The unit integrates components such as Schottky diodes and photodiodes, and has a front and back side. Through careful design, it produces different responses when facing microwave irradiation of different polarization directions. When the x-polarized incident wave is irradiated, it will be absorbed by the metasurface unit structure and rectified into DC energy to generate an optical signal. When the y-polarized incident wave is irradiated, its reflection amplitude will change with the light intensity on the photodiode. Multiple identical metasurface units are used to form an optical and microwave bidirectional signal conversion metasurface. Using the above-mentioned optical and microwave bidirectional signal conversion metasurface, bidirectional conversion of optical signals to microwave signals can be realized in free space without battery power, and the reflection phase of the incident microwave can be regulated by light, thereby constructing an optical and microwave bidirectional signal conversion metasurface platform.

[0033] Figure 1 and Figure 2 The front and back sides of the optical and microwave bidirectional signal conversion metasurface are shown respectively. Figure 3 The overall structure of the metasurface is shown. Figure 4 The metasurface unit structure is shown. Figures 1 to 3 As shown, the metasurface for forward conversion and reverse regulation of microwaves and light includes m×n identical metasurface units, where m and n are the number of rows and columns of the metasurface units, respectively; and also includes a first feeder network and a second feeder network.

[0034] like Figure 4 As shown, the double-sided metasurface unit includes a dielectric substrate 1, and a front resonant structure 2 and a back resonant structure 3 respectively located on the front and back of the dielectric substrate 1; the front resonant structure 2 includes: three sections of metal strips 21 arranged along the x-axis direction, the first and second sections of the metal strips are connected by a Schottky diode 22, and the second and third sections of the metal strips are connected by an inductor 23. Figure 1As shown, after the metal strips of adjacent double-sided metasurface units in the x direction in the array are connected in series, the two ends are respectively connected to the first metal strip 41 and the second metal strip 42 of the first feeder network. The metal strip 21 is used to absorb the incident microwave energy and provide a current transfer path, the Schottky diode 22 is used to rectify the incident microwave energy into DC energy, and the inductor 23 is used to connect adjacent metal strips to reduce electromagnetic coupling and filter out AC signals.

[0035] like Figure 4 As shown, the back resonant structure 3 includes: two metal sheets 31 arranged at intervals, and a photodiode 32 loaded between the two metal sheets arranged at intervals, and the photodiode 32 is used to receive different incident light intensities and generate capacitance changes to adjust the microwave reflection amplitude. Figure 2 As shown, the upper row of metal sheets 31 of adjacent double-sided metasurface units in the x-direction in the array are connected in series and are all connected to the third metal strip 51 of the second feeder network, and the lower row of metal sheets 31 are connected in series and are all connected to the fourth metal strip 52 of the second feeder network, so that all photodiodes 32 are connected in parallel. This enables the photodiodes of the entire metasurface to share the voltage at the same time when only the light intensity of one photodiode is adjusted.

[0036] Schottky diodes and photodiodes are loaded in the metasurface unit, which can be directly used as a platform for forward conversion and reverse regulation of microwave and optical information energy without relying on external power supply. On the one hand, the incident microwave signal can be converted into direct current and generate optical signals, realizing the conversion of microwave signals to optical signals. On the other hand, the reflection amplitude of microwaves can be changed by the incident optical signal, realizing the conversion of optical signals to microwave signals at the same time.

[0037] like Figure 5 As shown, as an optional solution, a resistor 33 may be loaded between two spaced metal sheets 31 , and the resistor 33 is connected in parallel with the photodiode 32 to construct a charge-discharge loop to obtain a higher response rate.

[0038] like Figure 1 and Figure 2 As shown, the first feeder network includes a first metal strip 41, a second metal strip 42, a first feeder 43, and a second feeder 44. The first metal strip 41 and the second metal strip 42 are arranged on the front side of the dielectric substrate 1, and the first feeder 43 and the second feeder 44 are arranged on the back side of the dielectric substrate 1. The first metal strip 41 and the second metal strip 42 are respectively connected to the first feeder 43 and the second feeder 44 through two metal through holes to provide the positive and negative electrodes of the DC energy. The first feeder 43 and the second feeder 44 are respectively connected to the positive and negative electrodes of the laser diode 6. The second feeder network includes a third metal strip 51 and a fourth metal strip 52. The third metal strip 51 and the fourth metal strip 52 are arranged on the back side of the dielectric substrate 1.

[0039] The Schottky diode 22 and photodiode 32 integrated in the metasurface unit are key components. Unlike other diodes, the Schottky diode contains a metal semiconductor MS junction, which has the advantages of low forward voltage drop and fast switching speed, and is very suitable for rectification. The Schottky diode 22 in this embodiment is used as a tuning element to complete the rectification process. When the laser is irradiated on the photodiode, the photodiode absorbs energy and produces a capacitance change according to the photoelectric capacitance effect, thereby affecting the microwave resonance characteristics of the metasurface unit. In this case, the amplitude of the reflected microwave is related to the intensity of the incident laser.

[0040] In the embodiment of the present invention, the metal strip 21 is a metal copper strip, and the two spaced metal sheets 31 are two identical metal copper sheets separated by a gap along the x direction, and the photodiode 32 is loaded at the gap.

[0041] The dielectric substrate 1 has a relative dielectric constant of 2.65, a loss tangent of 0.001, and a thickness of 2.0 mm.

[0042] The side length of the metasurface unit is 15.0 mm.

[0043] The forward conversion process from microwave signal to optical signal and the reverse conversion process from optical signal to microwave signal respectively adopt the cross-polarization mode of x-polarization and y-polarization to minimize coupling and interference.

[0044] In this embodiment, m=10, n=20, and 200 identical metasurface unit arrays are used to form a light and microwave bidirectional signal conversion metasurface. For microwave incident along the x direction, the metasurface front resonant structure 2 plays a resonant role, the metal strip 21 fully absorbs the incident microwave energy, and the Schottky diode 22 converts the incident microwave energy into DC energy to generate an optical signal; for microwave incident along the y direction, the microwave energy will pass through the front resonant structure 2 and the dielectric substrate 1, and reach the back resonant structure 3, and the back resonant structure 3 plays a resonant role. By adjusting the light intensity of the photodiode loaded on the back resonant structure 3, the reflection amplitude of the incident microwave can be flexibly adjusted, and the reverse conversion of the optical signal to the microwave signal can be realized.

[0045] In this embodiment, a HSMS-2860 Schottky diode and a Hamamatsu "S13773" PIN photodiode are used to form a metasurface unit.

[0046] Figure 6The reflection amplitude diagrams obtained by simulating the metasurface unit structure in two working modes in this embodiment are shown. It can be clearly observed that when the incident x-polarized microwave drives the Schottky diode in the "on" state, the metasurface unit produces a sharp resonance at around 4.00 GHz, which indicates that the incident microwave energy is well absorbed. The absorbed microwave energy can be further rectified by the Schottky diode to drive the laser diode to emit light to generate an optical signal, thereby realizing the forward conversion from microwave to laser. Under the incidence of y-polarized microwaves, the metasurface unit produces a resonant response, and as the incident laser power increases from 0 to 21.6 mW, the resonant frequency moves from 4.45 GHz to 3.92 GHz. At these two resonant frequencies, two reflection state amplitude differences of approximately 10 dB and 14 dB can be achieved, respectively, which can well realize the reverse regulation of laser to microwave.

[0047] Figure 7 The green laser power output measured at different incident microwave powers is shown. The input microwave power refers to the microwave power fed into the transmitting horn antenna at 4.06GHz. When the input x-polarized microwave power reaches 14dBm (25mW), the laser diode has been lit and the output laser power is 2.7mW. The microwave to laser conversion efficiency is calculated to be 10.8%. When the input microwave power increases to 24dBm (250mW), the output laser power reaches 16.2mW and the conversion efficiency is 6.48%.

[0048] Figure 8 The y-polarized microwave reflection amplitude measured under different power green laser irradiation is shown. When the irradiated laser power varies between 0 and 21.6 mW, the metasurface shows significantly different reflection amplitudes under y-polarized microwave incidence, with differences of 14 and 9 dB at 3.92 and 4.45 GHz, respectively. The measured results are in good agreement with the simulation results, verifying the effective control of laser to microwave.

[0049] The present invention also provides an optical and microwave bidirectional hybrid communication system constructed based on the metasurface. The switching laser intensity corresponds to two different microwave intensities, which indicates that the modulation and transmission of digital symbols "1" and "0" can be realized by using on-off keying (OOK) laser signals and binary amplitude shift keying (BASK) microwave signals. The system can transmit information through microwaves and recover the information through the generated laser demodulation; it can also control microwaves through laser emission information and demodulate and recover the information. Thus, two data (for example, two different videos) can be converted and transmitted independently and simultaneously through the same metasurface to realize bidirectional communication.

[0050] The metasurface can be used to construct a battery-free optical and microwave bidirectional communication system, and provide an effective solution for cross-media information transmission in the future integrated information network of air, land, and sea.

[0051] Fig. 9 The principle of a bidirectional hybrid communication system constructed by a bidirectional signal conversion metasurface for light and microwaves provided in an embodiment of the present invention is demonstrated. The full-duplex microwave laser hybrid wireless communication system spans two media, air and water, and mainly includes: a microwave end transmitter, a microwave end transceiver, a metasurface, a laser end receiver, and a laser end transmitter. The microwave end transmitter and the microwave end transceiver are located on the front side of the metasurface, and the laser end receiver and the laser end transmitter are located on the back side of the metasurface; the microwave end transmitter is composed of a software defined radio platform (NI USRP-2954), a power amplifier, and an x-polarized horn antenna, which is used to transmit amplified BASK signals. In the microwave end transceiver, the feed antenna (i.e., the y-polarized horn antenna) is connected to a microwave generator to transmit a y-polarized microwave signal, and the reflected BASK microwave signal is received by the y-polarized horn antenna and transmitted to the software defined radio platform connected to a computer for post-processing. The laser end transmitter includes a field programmable gate array (FPGA) and a green laser diode, which are used to generate an OOK laser signal with modulation information. The laser receiver includes a high-speed, high-sensitivity photoelectric detection and demodulation circuit, and performs signal post-processing through a computer.

[0052] In order to demonstrate the bidirectional full-duplex capability of the constructed microwave laser hybrid wireless communication system in cross-media communication, video image transmission is used as an example for demonstration. Fig. 9 As shown. In the forward conversion transmission link from microwave signal to laser signal, the video (blinking stars) is first converted into a data bit stream, which is encoded onto the BASK microwave signal through the microwave end transmitter to drive and modulate the metasurface, thereby generating a green OOK laser signal; after the generated OOK laser signal passes through the underwater, it is received by the photoelectric detection and demodulation circuit, and further demodulated into a digital baseband signal through the laser end receiver, and finally the video content is restored. In the reverse conversion transmission link from laser signal to microwave signal, the video (blooming lotus) is first converted into a data bit stream, which is encoded onto the underwater green OOK laser signal through the laser end transmitter, and illuminates the photodiode on the back of the metasurface; subsequently, the reflection amplitude response of the metasurface is rapidly changed; at this time, when the microwave end transceiver transmits y-polarized microwaves to the front of the metasurface, the reflected BASK microwave signal is received by the y-polarized horn antenna and demodulated into a digital baseband signal through the software defined radio platform, thereby restoring the video content.

[0053] The optical and microwave bidirectional signal conversion metasurface proposed in an embodiment of the present invention can directly complete the bidirectional conversion of optical signals and microwave signals without relying on an external power supply. At the same time, it can realize the energy conversion from microwaves to light, as well as the regulation of microwave reflection signals by light, providing an effective solution for cross-media information transmission in the future integrated information network of air, land, and sea.

[0054] The specific features, structures, materials or characteristics described in the embodiments or examples of this specification are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples without contradiction.

Claims

1. A metasurface for bidirectional signal conversion between light and microwaves, characterized in that: The invention comprises m×n double-sided metasurface units arranged in an array, a first feeder network and a second feeder network, wherein the double-sided metasurface units comprise a dielectric substrate (1), and a front resonant structure (2) and a back resonant structure (3) respectively located on the front and back sides of the dielectric substrate (1); the front resonant structures (2) in the same row arranged along the x direction in the array are connected in series, and the front resonant structures (2) in different rows arranged along the y direction are connected in parallel via the first feeder network and then connected to two ends of a laser diode; the back resonant structures (3) in the same row arranged along the x direction in the array are connected in series, and the back resonant structures (3) in different rows arranged along the y direction are connected in parallel via the second feeder network; When microwaves polarized along the x direction are irradiated onto the front side of the metasurface, the microwaves will be effectively absorbed by the front resonant structure (2) and rectified into direct current energy to drive the laser diode (6) to emit light, thereby realizing the forward conversion of microwave signals into optical signals. When microwaves polarized along the y direction are irradiated onto the front side of the metasurface, the microwaves will pass through the front resonant structure (2) and the dielectric substrate (1) and reach the back resonant structure (3). By adjusting the light intensity of the photodiode loaded on the back resonant structure, the reflection amplitude of the incident microwave can be flexibly controlled, and the reverse conversion of the optical signal into the microwave signal can be realized.

2. The optical and microwave bidirectional signal conversion metasurface according to claim 1, characterized in that: The front resonant structure (2) comprises three sections of metal strips (21) arranged along the x-axis direction, the first and second sections of the metal strips are connected via a Schottky diode (22), and the second and third sections of the metal strips are connected via an inductor (23); after the metal strips of adjacent double-sided metasurface units in the x-direction in the array are connected in series, the two ends are respectively connected to the first metal strip (41) and the second metal strip (42) of the first feeder network.

3. The optical and microwave bidirectional signal conversion metasurface according to claim 1, characterized in that: The back resonant structure (3) comprises two metal sheets (31) arranged at intervals, and a photodiode (32) loaded between the two metal sheets arranged at intervals, wherein the upper row of metal sheets of adjacent double-sided metasurface units in the array in the x direction are connected in series and are all connected to the third metal strip (51) of the second feeder network, and the lower row of metal sheets are connected in series and are all connected to the fourth metal strip (52) of the second feeder network, so that all the photodiodes (32) are connected in parallel.

4. The optical and microwave bidirectional signal conversion metasurface according to claim 3, characterized in that: The back side resonance structure (3) also includes a resistor (33), which is connected in parallel with the photodiode (32) and loaded between two spaced metal sheets (31) to construct a charge and discharge circuit.

5. The optical and microwave bidirectional signal conversion metasurface according to claim 3, characterized in that: The two spaced-apart metal sheets (31) are two identical metal copper sheets.

6. The optical and microwave bidirectional signal conversion metasurface according to claim 1, characterized in that: The first feeder network comprises a first metal strip (41), a second metal strip (42), a first feeder (43) and a second feeder (44); the first metal strip (41) and the second metal strip (42) are arranged on the front side of the dielectric substrate (1); the first feeder (43) and the second feeder (44) are arranged on the back side of the dielectric substrate (1); the first metal strip (41) and the second metal strip (42) are respectively connected to the first feeder (43) and the second feeder (44) through two metal through holes; the first feeder (43) and the second feeder (44) are respectively connected to the positive and negative electrodes of the laser diode (6).

7. The optical and microwave bidirectional signal conversion metasurface according to claim 1, characterized in that: The second feeder network comprises a third metal strip (51) and a fourth metal strip (52), and the third metal strip (51) and the fourth metal strip (52) are arranged on the back side of the dielectric substrate (1).

8. The optical and microwave bidirectional signal conversion metasurface according to claim 1, characterized in that: The material relative dielectric constant of the dielectric substrate (1) is 2.65, the loss tangent is 0.001, and the thickness is 2.0 mm.

9. A communication system based on the optical and microwave bidirectional signal conversion metasurface according to any one of claims 1 to 8, characterized in that: include: A light-to-microwave bidirectional signal conversion metasurface, a microwave transmitter and a microwave transceiver located on the front side of the metasurface, and a laser receiver and a laser transmitter located on the back side of the metasurface; In the forward conversion transmission link from microwave signals to optical signals, the signal to be transmitted is encoded onto the BASK microwave signal through the microwave end transmitter to drive and modulate the metasurface, thereby rectifying and generating a green OOK laser signal. The generated OOK laser signal is further demodulated into a digital baseband signal through the laser end receiver, and finally the signal to be transmitted is restored; In the reverse conversion transmission link from optical signal to microwave signal, the signal to be transmitted is first converted into a data bit stream, encoded onto an underwater green OOK laser signal by the laser-end transmitter, and irradiated with the photodiode on the back of the metasurface; subsequently, the reflection amplitude response of the metasurface is rapidly changed; at this time, when the microwave-end transceiver transmits y-polarized microwaves to the front of the metasurface, the reflected BASK microwave signal is received by the microwave-end transceiver and demodulated into a digital baseband signal through the software-defined radio platform, thereby restoring the video content.

10. The communication system according to claim 9, characterized in that: The optical and microwave bidirectional signal conversion metasurface, microwave transmitter and microwave transceiver are located in the air, and the laser receiver and laser transmitter are located in the water, achieving bidirectional full-duplex capability across the two media of air and water.

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