Terahertz Information Metasurface with Full Spatial Frequency Cross-Domain Coding

Abstract

This terahertz information metasurface with full-space spatial-frequency cross-domain coding solves the problem of how to effectively utilize electromagnetic resources throughout space to achieve ultrafast real-time switching between transmission and reflection states, belonging to the field of electromagnetic metamaterials. This application includes arrayed metasurface sub-units, which, from top to bottom, consist of a first frequency coding layer, a second dielectric layer, a third metal layer, a fourth dielectric layer, and a fifth transmission-reflection control layer. Real-time switching between reflection and transmission modes is achieved by controlling the conductivity state of photosensitive silicon in the fifth transmission-reflection control layer through wireless optical pumping. In reflection mode, the metasurface sub-units achieve frequency domain coding by regulating the excitation distribution of photosensitive silicon material in the first frequency coding layer; in transmission mode, the metasurface sub-units achieve spatial domain coding by regulating the excitation distribution of photosensitive silicon material in both the first and fifth transmission-reflection control layers, truly realizing cross-domain collaborative modulation at the full-space level.

Description

Technical Field

[0001] This application relates to a terahertz information metasurface with full-space frequency cross-domain coding, belonging to the field of electromagnetic metamaterials. Background Technology

[0002] Metasurfaces, as two-dimensional planar devices composed of subwavelength artificial microstructure arrays, exhibit remarkable capabilities in flexibly controlling parameters such as the amplitude, phase, and polarization of electromagnetic waves. With the development of terahertz technology, terahertz metasurfaces have emerged, providing an effective solution to the problem of the lack of efficient control devices in the terahertz band. In particular, the concept of digitally coded metasurfaces introduces the digital coding concept from information science into the field of electromagnetic metamaterials. Traditional digitally coded metasurfaces are typically designed in the spatial domain, using the specific phase response of different microstructure units to incident electromagnetic waves to represent digital states (for example, two units with a phase difference of 180 degrees are defined as the digits "0" and "1," respectively). By changing the spatial arrangement topology of these coding units, a variety of electromagnetic functions can be achieved, such as beamforming, anomalous deflection, and radar cross-section reduction.

[0003] However, traditional spatially coded metasurfaces typically require that the phase difference between coded units remain as consistent as possible within the operating frequency band during design. This results in coded metasurface sub-units corresponding to the same coded state across the entire operating frequency band. Therefore, once the coded pattern is determined, its electromagnetic response and function are fixed, enabling only a single electromagnetic function and making it difficult to adapt to complex and ever-changing application scenarios. To overcome this static limitation, the concept of frequency-coded metasurfaces has been proposed. The most significant characteristic of frequency-coded metasurfaces is that the phase response curves of their units exhibit different trends within the operating frequency band. In other words, different units demonstrate distinctly different phase-frequency sensitivities. Utilizing this difference in phase-frequency sensitivity, the equivalent phase gradient of the metasurface can be dynamically evolved by changing the operating frequency of the incident electromagnetic wave. This mechanism enables smooth beam deflection simply by changing the incident frequency, without relying on a complex external active control network.

[0004] Despite significant progress made in low-frequency coded metasurfaces in the aforementioned spatial and frequency domains, substantial challenges remain in their practical application in the terahertz band. On one hand, the extremely short wavelength of terahertz waves leads to severe parasitic effects in traditional electrically controlled active devices (such as diodes), and the high-density control networks are difficult to physically integrate with extremely small metasurface sub-units, resulting in a lack of mature high-density phase shifters in this band. On the other hand, existing terahertz coded metasurfaces are often limited to single transmission or reflection half-space manipulation, and their coding dimension is singular (spatial or frequency domain only), failing to effectively utilize electromagnetic resources across the entire space. Summary of the Invention

[0005] To address the challenge of effectively utilizing electromagnetic resources across the entire space to achieve ultrafast real-time switching between transmission and reflection states, this application provides a terahertz information metasurface with full-space spatial frequency cross-domain coding.

[0006] This application discloses a terahertz information metasurface with full-space-frequency cross-domain coding, comprising metasurface sub-units arranged in an array, the metasurface sub-units consisting of five layers from top to bottom:

[0007] The system comprises a first frequency coding layer, a second dielectric layer, a third metal layer, a fourth dielectric layer, and a fifth transmission-reflection control layer; wherein the first frequency coding layer and the fifth transmission-reflection control layer both contain photosensitive silicon material.

[0008] By wirelessly pumping and controlling the conductivity state of the photosensitive silicon in the fifth transmission-reflection control layer, the metasurface subunits can switch between reflection and transmission modes in real time.

[0009] In reflection mode, the metasurface subunit achieves frequency domain coding by controlling the excitation distribution of photosensitive silicon material in the first frequency coding layer, thereby controlling the terahertz wave in the reflection half-space;

[0010] In transmission mode, the metasurface subunit achieves spatial coding by regulating the excitation distribution of photosensitive silicon material in the first frequency coding layer and the fifth transmission-reflection control layer, so as to regulate the terahertz wave in the transmission half space.

[0011] This establishes an orthogonal mapping mechanism between the working mode and the coding domain, enabling full-space cross-domain coordinated modulation of terahertz waves.

[0012] Preferably, the photosensitive silicon in the fifth transmission-reflection control layer in the reflection mode is fully excited to a metal-like state and used as a ground plane.

[0013] Preferably, the frequency domain coding in the reflection mode is 2-bit frequency domain coding:

[0014] By changing the excitation distribution of the photosensitive silicon material in the first frequency coding layer, four frequency coding units with different phase frequency sensitivities are defined, corresponding to coding states 0, 1, 2, and 3, respectively.

[0015] The photosensitive silicon in the fifth transmission-reflection control layer is fully excited to a metallic-like state and used as a ground plane.

[0016] Preferably, the frequency coding units in the reflection mode are arranged according to a spatial aperiodic topological coding sequence designed using the phase-frequency sensitivity gradient difference.

[0017] Preferably, the spatial coding in the transmission mode is 1-bit spatial coding: by adjusting the excitation distribution of the photosensitive silicon material in the first frequency coding layer and the fifth transmission-reflection control layer, two coding states are defined, corresponding to coding state 0 and coding 1 respectively.

[0018] As a preferred embodiment, the first frequency coding layer is:

[0019] A strip-shaped metal resonator is set on the top, bottom, left, and right sides of the No. 1 cross-shaped photosensitive silicon block;

[0020] A cross-shaped photosensitive silicon block No. 1 has a cross-shaped metal resonator at its center, and the four ends of the cross-shaped metal resonator No. 1 extend to the top, bottom, left and right sides of the strip-shaped metal resonator No. 1, respectively.

[0021] The No. 1 cross-shaped metal resonator divides the cross-shaped photosensitive silicon block into four symmetrical L-shaped pumping regions. The photosensitive silicon in each L-shaped pumping region is divided into a first L-shaped region, a second L-shaped region, and a third L-shaped region from the inside out. Each L-shaped region is connected to a No. 1 strip-shaped metal resonator at both ends. Each L-shaped region is in an insulating state or a metallic state.

[0022] Preferably, the third metal layer is:

[0023] An L-shaped metal resonator is placed at each of the four corners of the square photosensitive silicon block.

[0024] Preferably, the fifth transmission-reflection control layer is:

[0025] A strip-shaped metal resonator is set on the top, bottom, left, and right sides of the square photosensitive silicon block No. 2, respectively;

[0026] A No. 2 cross-shaped metal resonator is set at the center of the No. 2 square photosensitive silicon block. The four ends of the No. 2 cross-shaped metal resonator extend to the No. 2 strip-shaped metal resonator on the upper, lower, left and right sides, respectively.

[0027] An L-shaped cutout is set between two adjacent No. 2 strip metal resonators, so that the No. 2 square photosensitive silicon block includes a central cross-shaped photosensitive silicon region and four corner pump regions.

[0028] As a preferred option , , , , , , , , , , ;

[0029] The length of the No. 1 strip-shaped metal resonator in the first frequency coding layer;

[0030] The width of the No. 1 strip-shaped metal resonator in the first frequency coding layer;

[0031] The width of the cross-shaped photosensitive silicon region in the middle of the fifth transmission-reflection control layer;

[0032] The length of the cross-shaped photosensitive silicon region in the middle of the fifth transmission-reflection control layer;

[0033] The linewidths of cross-shaped metal resonators No. 1 and No. 2 are given.

[0034] The physical period of the metasurface subunit;

[0035] The linewidth of the L-shaped metal resonator at the four corners of the third metal layer;

[0036] The side lengths of the L-shaped metal resonant rings at the four corners of the third metal layer;

[0037] The line width of the cross shape enclosed by the first L-shaped region in the first frequency coding layer;

[0038] The line width of the cross shape formed by the first L-shaped region and the second L-shaped region in the first frequency coding layer;

[0039] The linewidth of the cross-shaped photosensitive silicon region formed by the four L-shaped pump regions in the first frequency coding layer.

[0040] As a preferred method, wireless optical pumping is achieved through spatially coded structured light.

[0041] The beneficial effects of this application are that the metasurface of this invention can independently control terahertz beams incident in two half-spaces and achieve real-time switching between transmission and reflection states through wireless optical control. Its core mechanism lies in establishing a synergy between "operating mode and coding domain": in the reflection state, frequency domain coding is performed using the different phase-frequency sensitivity differences between sub-units to achieve continuous deflection control of the far-field beam; in the transmission state, the sub-units perform spatial domain coding to complete wavefront shaping, thereby truly achieving cross-domain collaborative modulation at the full spatial level. This invention breaks through the static limitations of traditional metasurfaces, possessing excellent dynamic reconfigurability, and enabling flexible switching of electromagnetic functions through spatially encoded structured light. This invention effectively opens up the path for space-frequency cross-domain collaborative modulation, and has enormous application potential in future 6G communication, wireless terahertz communication, and intelligent reconfigurable systems. Specifically, it includes:

[0042] 1. Breaking through static limitations and achieving full-space dynamic reconfigurability: The structure designed in this application has excellent dynamic reconfigurability and can flexibly adapt to the needs of multiple scenarios. Wireless control is achieved through spatially coded structured light, and the photoconductive effect of photosensitive silicon enables the device to switch between transmission and reflection modes in ultra-fast real time, breaking through the static response limitations of traditional frequency-coded metasurfaces.

[0043] 2. Innovative cross-domain collaborative modulation for efficient utilization of space electromagnetic resources: This application breaks through the limitations of single-dimensional coding, proposes a space-frequency cross-domain collaborative design, and establishes a unique "working mode-coding domain" orthogonal mapping mechanism. The system achieves 2-bit frequency domain dispersive beam continuous control in reflection mode and 1-bit spatial wavefront shaping in transmission mode, effectively opening up the path for cross-domain collaborative modulation and enabling efficient utilization of electromagnetic resources throughout space.

[0044] 3. Possesses broad application prospects in next-generation intelligent networks: This application solves the problem that existing devices are difficult to connect to networks as programmable intelligent nodes, providing a new technical approach for building highly integrated terahertz intelligent reconfigurable systems. It demonstrates enormous application potential in cutting-edge fields such as future 6G communication, wireless terahertz communication, sensor integration, and intelligent electromagnetic countermeasures. Attached Figure Description

[0045] Figure 1 This is a structural diagram of the metasurface subunit in this application;

[0046] Figure 2 This is a schematic diagram of 2-bit frequency domain coding in reflection mode of this application;

[0047] Figure 3 This is a schematic diagram of 1-bit spatial coding in the transmission mode of this application;

[0048] Figure 4These are the simulation results of the reflection amplitude and phase of the metasurface subunit under different optical pumping states in this application;

[0049] Figure 5 These are the transmission amplitude results of the metasurface subunits of this application under different optical pumping states;

[0050] Figure 6 This is a simulated three-dimensional far-field scattering pattern of dual beams in reflection mode (frequency domain coding) according to this application;

[0051] Figure 7 This is a simulated three-dimensional far-field scattering pattern of four beams in reflection mode (frequency domain coding) according to this application;

[0052] Figure 8 This is a simulated three-dimensional far-field scattering pattern of dual-beam / quad-beam in transmission mode (spatial coding) according to this application;

[0053] Figure 9 This is a schematic diagram of 1-bit spatial coding (aperiodic coding sequence) in the transmission mode of this application. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0055] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0056] The present application will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the application.

[0057] The core of this application lies in achieving ultrafast real-time switching between transmission and reflection states through wireless optical control, and independently controlling the terahertz beams incident in two half-spaces. The full-space spatial-frequency cross-domain encoded terahertz information metasurface of this embodiment establishes a unique "working mode-coding domain" orthogonal mapping mechanism. That is, in the reflection state, the metasurface sub-units perform frequency domain encoding, while in the transmission state, the sub-units perform spatial domain encoding, thus truly achieving cross-domain encoding and modulation at the full-space level. The full-space spatial-frequency cross-domain encoded terahertz information metasurface of this embodiment includes metasurface sub-units arranged in an array, and the metasurface sub-units consist of a five-layer structure from top to bottom:

[0058] The system comprises a first frequency coding layer, a second dielectric layer, a third metal layer, a fourth dielectric layer, and a fifth transmission-reflection control layer; wherein,

[0059] The first frequency coding layer contains a patterned first photosensitive silicon region, while the second and fourth layers are dielectric layers. The fifth transmission-reflection control layer contains a patterned second photosensitive silicon region. The photoconductivity of the first and second photosensitive silicon regions can be wirelessly controlled to independently regulate the terahertz beams incident in the two half-spaces.

[0060] The two photosensitive silicon regions operate based on the photoconductivity effect. Without pump excitation, the conductivity of the photosensitive silicon is 0; when pump excitation is present, the conductivity of the photosensitive silicon is controlled by the pump light power, enabling independent modulation of the two half-space incident terahertz beams. In this embodiment, wireless optical pumping is achieved through spatially coded structured light. By precisely controlling the state of the photosensitive silicon in the fifth layer, rapid switching between reflection and transmission modes can be achieved.

[0061] In reflection mode, the metasurface subunit achieves frequency domain coding by controlling the excitation distribution of the photosensitive silicon material in the first frequency coding layer, thereby controlling the terahertz wave in the reflection half-space. Specifically, a 2-bit frequency domain coding mechanism is used to achieve frequency dispersive beam scanning. At this time, the second photosensitive silicon region of the five transmission-reflection control layers is fully excited to a metallic-like state and serves as a ground plane. By changing the spatial distribution of the first photosensitive silicon region of the first frequency coding layer between the ground state and the excited state, four frequency coding units with different phase frequency sensitivities are defined, corresponding to coding states 0, 1, 2, and 3, respectively, thereby realizing the 2-bit frequency domain coding mechanism.

[0062] As the coding unit number ("0" to "3") increases, the slope of its phase response curve gradually increases, reflecting different phase-frequency sensitivities. The frequency coding units are arranged according to a spatial aperiodic topological coding sequence designed using the gradient difference in phase-frequency sensitivity, enabling continuous "frequency-controlled space" manipulation of electromagnetic waves. Without the need for a complex external active control network, simply by tuning the incident frequency, the far-field main beam can be driven to produce regular, continuous deflections in space.

[0063] In transmission mode, the metasurface subunit achieves spatial coding by adjusting the excitation distribution of photosensitive silicon material in the first frequency coding layer and the fifth transmission-reflection control layer, thereby controlling the terahertz wave in the transmission half-space. Specifically, this embodiment utilizes 1-bit spatial coding to achieve flexible and programmable wavefront shaping. By adjusting the excitation distribution of photosensitive silicon in the top and bottom layers of the unit, the switching between coded "0" and "1" is achieved. For example, at a center operating frequency of 0.55 THz, both spatial coding units can achieve a high transmission amplitude of -2.03 dB, ensuring extremely low electromagnetic loss, and the phase difference between them is precisely 180°, meeting the requirements of digital spatial phase control and supporting efficient bidirectional or four-way electromagnetic energy distribution and spatial beamforming.

[0064] The two modes mentioned above establish an orthogonal mapping mechanism between the working mode and the coding domain, enabling full-space cross-domain coordinated modulation of terahertz waves.

[0065] In this embodiment, the second and fourth dielectric layers are composed of UV-curable adhesive; the third metal layer is made of metallic silver. Figure 1 As shown, in this embodiment, the first frequency coding layer is:

[0066] A strip-shaped metal resonator is set on the top, bottom, left, and right sides of the No. 1 cross-shaped photosensitive silicon block;

[0067] A cross-shaped photosensitive silicon block No. 1 has a cross-shaped metal resonator at its center, and the four ends of the cross-shaped metal resonator No. 1 extend to the top, bottom, left and right sides of the strip-shaped metal resonator No. 1, respectively.

[0068] The first cross-shaped metal resonator divides the cross-shaped photosensitive silicon block into four symmetrical L-shaped pump regions. Within each L-shaped pump region, the photosensitive silicon is sequentially divided into a first L-shaped region, a second L-shaped region, and a third L-shaped region from the inside out. Each L-shaped region is connected to a strip-shaped metal resonator (number 1) at both ends. Each L-shaped region is in an insulating or metallic state. The cross-shaped photosensitive silicon region formed by the four L-shaped pump regions is the first photosensitive silicon region.

[0069] In this embodiment, the third metal layer is:

[0070] An L-shaped metal resonator is placed at each of the four corners of the square photosensitive silicon block.

[0071] In this embodiment, the fifth transmission-reflection control layer is:

[0072] A strip-shaped metal resonator is set on the top, bottom, left, and right sides of the square photosensitive silicon block No. 2, respectively;

[0073] A No. 2 cross-shaped metal resonator is set at the center of the No. 2 square photosensitive silicon block. The four ends of the No. 2 cross-shaped metal resonator extend to the No. 2 strip-shaped metal resonator on the upper, lower, left and right sides, respectively.

[0074] An L-shaped cutout is set between two adjacent No. 2 strip metal resonators, so that the No. 2 square photosensitive silicon block includes a central cross-shaped photosensitive silicon region and four corner pump regions, which is the second photosensitive silicon region.

[0075] like Figure 1 As shown, different colors in the first frequency coding layer represent different areas of photosensitive silicon. The second and fourth layers are dielectric layers, consisting of a thickness of [missing information]. It consists of ultraviolet-curing adhesive (UV adhesive).

[0076] The fifth layer serves as a transmission-reflection control layer. By controlling the state of the photosensitive silicon within the red region, this unit can rapidly switch between reflection and transmission modes. The relevant structural parameters are as follows: , , , , , , , , , .

[0077] The length of the No. 1 strip-shaped metal resonator in the first frequency coding layer; The width of the No. 1 strip-shaped metal resonator in the first frequency coding layer; The width of the cross-shaped photosensitive silicon region in the middle of the fifth transmission-reflection control layer; The length of the cross-shaped photosensitive silicon region in the middle of the fifth transmission-reflection control layer; The linewidths of cross-shaped metal resonators No. 1 and No. 2 are given. The physical period of the metasurface subunit; The linewidth of the L-shaped metal resonator at the four corners of the third metal layer; The side lengths of the L-shaped metal resonant rings at the four corners of the third metal layer; The line width of the cross shape enclosed by the first L-shaped region in the first frequency coding layer; The linewidth is the cross-shaped area enclosed by the first L-shaped region and the second L-shaped region in the first frequency coding layer. The linewidth of the cross-shaped photosensitive silicon region formed by the four L-shaped pump regions in the first frequency coding layer.

[0078] like Figure 2 and Figure 3Figure 2 illustrates the photosensitive silicon excitation states of the metasurface subunits designed in this embodiment under different operating modes. Figure 2 depicts the 2-bit frequency encoding states in reflection mode. By changing the distribution of the first photosensitive silicon region between the ground state (gray) and excited state (green), four encoding units with different phase frequency sensitivities are defined. This gradient state change aims to generate four different phase responses, thereby achieving "frequency encoding." Figure 2 shows that in reflection mode, the second photosensitive silicon region is in a fully excited metallic-like state to act as a ground plane. Figure 3 This demonstrates the 1-bit spatial coding state in transmission mode. By adjusting the photosensitive silicon excitation distribution at the top and bottom layers of the unit, the coding "0" and "1" are switched, thereby generating a specific phase difference while ensuring electromagnetic wave transmission. These two figures together illustrate how this design utilizes the dynamic evolution characteristics of photosensitive silicon conductivity to integrate transmission-reflection switching and spatial-frequency cross-domain coding functions within a single structure. Figure 4 and Figure 5 The system demonstrates the electromagnetic response characteristics of the designed metasurface subunit in both reflection and transmission modes.

[0079] Traditional coded metasurfaces are designed to maintain a consistent phase difference between their sub-units across the operating frequency band. This results in each sub-unit corresponding to the same coded state throughout the entire band. Consequently, once the coded pattern is determined, the coded metasurface can only perform a single electromagnetic function. The most significant characteristic of frequency-coded metasurfaces is that the phase response curves of their units exhibit different trends across the operating frequency band. Figure 4 This study demonstrates the 2-bit frequency coding characteristics in reflection mode. By simulating the responses of four coding units ("0" to "3") under different optical pumping states, it is found that subunits with different resonant intensities exhibit drastically different phase-frequency sensitivities near the resonant frequency. As the coding sequence number increases from "0" to "3", the slope of its phase response curve gradually increases. This linear evolution of phase with frequency is the core physical mechanism for realizing frequency domain information coding and frequency scanning beams. Figure 5 The 1-bit spatial coding characteristics in transmission mode were demonstrated: at a center operating frequency of 0.55 THz, the transmission amplitude of both spatial coding units "0" and "1" reached a high of -2.03 dB, ensuring low electromagnetic loss. Simultaneously, at this frequency, the phase difference between the two coded states was precisely 180°, meeting the requirements of 1-bit digital spatial phase modulation, thus supporting efficient spatial beamforming and dynamic scanning.

[0080] Figure 6 and Figure 7The three-dimensional far-field scattering response of the metasurface array is shown in the range of 0.68 THz to 1.13 THz. Within this wide bandwidth, the far-field multibeams exhibit significant frequency dispersion scanning characteristics as the operating frequency evolves. Specifically, the frequency-domain coding mechanism enables the equivalent phase gradient of the array surface to dynamically respond with frequency, thereby driving the azimuth and elevation angles of the beams to produce regular and continuous deflections in space. This mapping relationship between frequency and spatial pointing intuitively demonstrates the ability of this metasurface to flexibly control spatial beams using the frequency dimension, providing a reliable physical approach for terahertz frequency-space division multiplexing. Figure 8 The modulation efficiency of pure spatial coding in transmission mode was further verified. The results show that this mode also supports bidirectional or four-way electromagnetic energy distribution with high isolation. This phenomenon confirms that the designed device not only has high-degree-of-freedom wavefront shaping capability in a single physical domain, but also more effectively opens up the path for cross-domain spatial-frequency cooperative modulation.

[0081] like Figure 9 As shown, this application proposes a 2-bit frequency domain coding sequence based on spatial aperiodic topology in reflection mode. Figure 9 The far-field evolution of the array within the 1.02 THz to 1.14 THz frequency band was systematically demonstrated. In this mode, this implementation explored and verified a unique "frequency-controlled space" mechanism: without any complex external active control network, the far-field main beam can be driven to achieve a smooth, monotonically deflected motion from 7° to 13° in space simply by continuously tuning the frequency of the incident electromagnetic wave. The successful realization of this scanning characteristic relies heavily on the proposed aperiodic coding topology.

[0082] In summary, this invention proposes and verifies a full-space-frequency cross-domain coded terahertz information metasurface, achieving integrated and dynamic switching of transmission and reflection modes through wireless optical control. This application is not limited to single-dimensional coding but proposes a cross-domain collaborative design of the spatial and frequency domains. Through the collaborative design of the "working mode-coding domain," this embodiment verifies the use of 2-bit frequency domain coding to achieve frequency-dependent beam scanning and control in reflection mode, and the use of 1-bit spatial domain coding to achieve beam control in transmission mode. This breaks through the static response limitations of traditional frequency-coded metasurfaces, and its wireless optical control and full-space beam control provide new technical paths for intelligent communication, radar stealth, and other applications. After equivalent scaling of the unit structure size and adjustment of relevant material parameters, the proposed space-frequency cross-domain coding mechanism can also be extended to other electromagnetic frequency bands such as microwaves and millimeter waves.

[0083] While this application has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of this application. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of this application as defined by the appended claims. It should be understood that different dependent claims and features herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other embodiments.

Claims

1. A terahertz information metasurface with full-space-frequency cross-domain coding, characterized in that, It includes metasurface sub-units arranged in an array, each metasurface sub-unit consisting of five layers from top to bottom: The system comprises a first frequency coding layer, a second dielectric layer, a third metal layer, a fourth dielectric layer, and a fifth transmission-reflection control layer; wherein the first frequency coding layer and the fifth transmission-reflection control layer both contain photosensitive silicon material. By wirelessly pumping and controlling the conductivity state of the photosensitive silicon in the fifth transmission-reflection control layer, the metasurface subunits can switch between reflection and transmission modes in real time. In reflection mode, the metasurface subunit achieves frequency domain coding by regulating the excitation distribution of photosensitive silicon material in the first frequency coding layer, thereby regulating the terahertz wave in the reflection half-space. In transmission mode, the metasurface subunit achieves spatial coding by regulating the excitation distribution of photosensitive silicon material in the first frequency coding layer and the fifth transmission-reflection control layer, so as to regulate the terahertz wave in the transmission half space. This establishes an orthogonal mapping mechanism between the working mode and the coding domain, enabling full-space cross-domain coordinated modulation of terahertz waves.

2. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 1, characterized in that, In the reflection mode, the photosensitive silicon in the fifth transmission-reflection control layer is fully excited to a metal-like state and used as a ground plane.

3. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 1, characterized in that, The frequency domain coding in the reflection mode is 2-bit frequency domain coding: By changing the excitation distribution of the photosensitive silicon material in the first frequency coding layer, four frequency coding units with different phase frequency sensitivities are defined, corresponding to coding states 0, 1, 2, and 3, respectively. The photosensitive silicon in the fifth transmission-reflection control layer is fully excited to a metallic-like state and used as a ground plane.

4. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 3, characterized in that, The frequency coding units in the reflection mode are arranged according to a spatial aperiodic topological coding sequence designed using the phase-frequency sensitivity gradient difference.

5. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 3, characterized in that, The spatial coding in the transmission mode is 1-bit spatial coding: by adjusting the excitation distribution of the photosensitive silicon material in the first frequency coding layer and the fifth transmission-reflection control layer, two coding states are defined, corresponding to coding state 0 and coding 1 respectively.

6. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 3, characterized in that, The first frequency coding layer is: A strip-shaped metal resonator is set on the top, bottom, left, and right sides of the No. 1 cross-shaped photosensitive silicon block; A cross-shaped metal resonator is provided at the center of the No. 1 cross-shaped photosensitive silicon block, and the four ends of the No. 1 cross-shaped metal resonator extend to the No. 1 strip-shaped metal resonator on the upper, lower, left and right sides, respectively. The No. 1 positive cross metal resonator divides the cross-shaped photosensitive silicon block into four symmetrical L-shaped pumping regions. The photosensitive silicon in each L-shaped pumping region is divided into a first L-shaped region, a second L-shaped region, and a third L-shaped region from the inside out. Each L-shaped region is connected to a No. 1 strip metal resonator at both ends. Each L-shaped region is in an insulating state or a metallic state.

7. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 6, characterized in that, The third metal layer is: An L-shaped metal resonator is placed at each of the four corners of the square photosensitive silicon block.

8. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 7, characterized in that, The fifth transmission-reflection control layer is: A strip-shaped metal resonator is set on the top, bottom, left, and right sides of the square photosensitive silicon block No. 2, respectively; A No. 2 cross-shaped metal resonator is disposed at the center of the No. 2 square photosensitive silicon block, and the four ends of the No. 2 cross-shaped metal resonator extend to the No. 2 strip-shaped metal resonator on the upper side, lower side, left side and right side respectively. An L-shaped cutout is set between two adjacent No. 2 strip metal resonators, so that the No. 2 square photosensitive silicon block includes a central cross-shaped photosensitive silicon region and four corner pump regions.

9. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 6, characterized in that, ， ， ， ， ， ， ， , , , ； The length of the No. 1 strip-shaped metal resonator in the first frequency coding layer; The width of the No. 1 strip-shaped metal resonator in the first frequency coding layer; The width of the cross-shaped photosensitive silicon region in the middle of the fifth transmission-reflection control layer; The length of the cross-shaped photosensitive silicon region in the middle of the fifth transmission-reflection control layer; The linewidths of cross-shaped metal resonators No. 1 and No. 2 are given. The physical period of the metasurface subunit; The linewidth of the L-shaped metal resonator at the four corners of the third metal layer; The side lengths of the L-shaped metal resonant rings at the four corners of the third metal layer; The line width of the cross shape enclosed by the first L-shaped region in the first frequency coding layer; The line width of the cross shape formed by the first L-shaped region and the second L-shaped region in the first frequency coding layer; The linewidth of the cross-shaped photosensitive silicon region formed by the four L-shaped pump regions in the first frequency coding layer.

10. The terahertz information metasurface with full-space-frequency cross-domain coding according to claim 1, characterized in that, The wireless optical pumping is achieved through spatially coded structured light.

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