Super-large octave wave absorber based on photoconductive material

Abstract

The invention discloses an ultra-large octave wave absorber based on a photoconductive material, and belongs to the field of electromagnetic metasurfaces and metamaterials. Comprising a light response wave-absorbing metasurface and a light driving module capable of projecting different patterns on the surface of the light response wave-absorbing metasurface, array wave-absorbing units of different sizes are obtained on the light response wave-absorbing metasurface by switching the projected patterns, and impedance of a target frequency band is matched by changing equivalent capacitance / inductance of a wave-absorbing unit structure; the light driving module can project a preset light pattern on the light response wave-absorbing metasurface, so that the equivalent impedance distribution of the light response wave-absorbing metasurface is changed; according to the light response wave-absorbing metasurface, the conductivity distribution of the metasurface units is changed through light control, and the wave-absorbing frequency band is adjusted in real time, that is, dynamic adjustment of the wave-absorbing performance is achieved through non-contact light control. According to the invention, the limitation of narrow bandwidth and passive fixation of a traditional wave absorber is broken through, and electromagnetic wave control with ultra-large octave, high absorptivity and real-time reconfigurability is realized.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic metasurfaces and metamaterials, and particularly relates to an absorber with an ultra-wide octave based on a photoconductive material. Background Art

[0002] With the rapid development of global wireless communication technologies, radar detection systems, electromagnetic compatibility (EMC), and stealth technologies, the number of various electronic devices and electromagnetic wave radiation sources has increased sharply, and the electromagnetic environment has become increasingly complex, resulting in an increasingly serious electromagnetic interference (EMI) problem. At the same time, in fields such as aerospace, 5G / 6G communication, and high-frequency electronic systems, the demand for precise electromagnetic wave regulation continues to increase. How to efficiently absorb electromagnetic waves in a wider frequency range and reduce interference between systems has become an important research topic in the current electromagnetic wave control field.

[0003] Traditional absorber technologies have made significant progress in electromagnetic wave shielding, stealth materials, electromagnetic environment optimization, etc. Typical absorbing materials include ferrite materials, carbon-based materials (such as graphene, carbon nanotubes), conductive polymers, and metamaterials. These absorbers usually rely on the dielectric loss or magnetic loss of the material to absorb electromagnetic wave energy and convert it into heat energy or other forms of energy. However, traditional absorbing materials have obvious limitations in the following aspects: the working frequency bands of most traditional absorbing materials are relatively limited, and they can usually achieve efficient absorption only in a single or a few fixed frequency bands; the effective absorption range of the absorber is usually restricted by the complex permittivity and complex permeability of the material, and it is difficult to flexibly regulate; low-frequency absorption usually requires a thicker material, while high-frequency absorption requires a thinner material, making it difficult to balance the ultra-wide frequency characteristics; traditional absorbers are usually passive structures, and once designed, their absorption performance and working frequency band are basically fixed and cannot be dynamically regulated in real time. Summary of the Invention

[0004] Technical Problems to be Solved

[0005] In order to avoid the deficiencies of the prior art, the present invention provides an absorber with an ultra-wide octave based on a photoconductive material. Through the frequency-variable dissipation mechanism of the light-responsive absorbing metasurface, wide-frequency absorption across an octave is achieved; through the dynamic regulation of the photoconductive material, the design of a transparent flexible structure, and the high-speed response of the light-driven module, the limitations of narrow bandwidth and passive fixation of traditional absorbers are broken through, and electromagnetic wave control with an ultra-wide octave, high absorption rate, and real-time reconfigurability is realized.

[0006] The technical solution of the present invention is: an absorber with an ultra-wide octave based on a photoconductive material, including a light-responsive absorbing metasurface and a light driving module capable of projecting different patterns on its surface. By switching the projected patterns, array absorbing units of different sizes are obtained on the light-responsive absorbing metasurface, and the impedance of the target frequency band is matched by changing the equivalent capacitance / inductance of the absorbing unit structure; the light driving module can project a preset light pattern on the light-responsive absorbing metasurface, thereby changing the equivalent impedance distribution of the light-responsive absorbing metasurface; the light-responsive absorbing metasurface changes the conductivity distribution of the metasurface unit through light control, and adjusts the absorbing frequency band in real time, that is, realizes the dynamic adjustment of the absorbing performance through non-contact light control.

[0007] A further technical solution of the present invention is: the light-responsive absorbing metasurface is a layered structure sequentially integrated with an OPC photoconductive layer, a polydimethylsiloxane PDMS dielectric layer, and an indium tin oxide ITO transparent conductive thin film layer. The OPC photoconductive layer and the indium tin oxide ITO transparent conductive thin film layer are coupled through the polydimethylsiloxane PDMS dielectric layer to achieve gradient impedance matching, so as to reduce the interface reflection of electromagnetic waves between the OPC photoconductive layer and the indium tin oxide ITO transparent conductive thin film layer.

[0008] A further technical solution of the present invention is: the thickness of the OPC photoconductive layer is 10–20μm, and under the illumination with a wavelength of 780nm and a power density ≥5mW / cm 2 , the resistivity drops from 106Ω·cm to 10 2 Ω·cm, and the response time ≤100μs.

[0009] A further technical solution of the present invention is: the thickness of the indium tin oxide ITO transparent conductive thin film layer is 150±5nm, the light transmittance in the 550nm visible light band ≥85%, the sheet resistance ≤8Ω / □, and the haze value ≤2%.

[0010] A further technical solution of the present invention is: the impedance ratio of the OPC photoconductive layer to the indium tin oxide ITO transparent conductive thin film layer is 10 3 –104, and a frequency-variable absorption mechanism with a dissipation ratio of 62% of the OPC photoconductive layer at 6.2GHz and a dissipation ratio of 58% of the OPC photoconductive layer at 24.6GHz.

[0011] A further technical solution of the present invention is: the polydimethylsiloxane PDMS dielectric layer is doped with 5wt% titanium dioxide nanoparticles, the thickness is 0.5mm, the relative dielectric constant ε = 2.1466, and the loss tangent tanδ = 0.0269.

[0012] A further technical solution of the present invention is: the thickness deviation of the polydimethylsiloxane PDMS dielectric layer is controlled within ±5%, so as to avoid the decrease in absorption rate caused by the standing wave effect.

[0013] A further technical solution of the present invention is that the light driving module is a DLP projection module, including a DMD chip, an FPGA controller, and a laser. The DMD chip contains a micromirror array of 415×315 with a pitch of 10.8μm, and the minimum projection feature size is 7.6μm. The FPGA controller generates a Gray code sequence to control the flipping of the micromirrors, and the pattern switching time ≤ 20μs. The synchronization delay between the laser and the DMD chip is < 50ns, and several resonant unit patterns are pre-stored and support real-time calling.

[0014] A further technical solution of the present invention is that in the TE / TM mode, when the incident angle is 0° to 60°, the average absorption rate of the absorber is ≥ 90%, and it can conform to the curved surface.

[0015] A method for dynamically regulating electromagnetic waves, the specific steps are as follows:

[0016] Project a target light pattern onto the OPC photoconductive layer through the DLP projection module to form a conductive area;

[0017] Adjust the size and distribution of the projection pattern to match the equivalent capacitance / inductance of the target frequency band;

[0018] Utilize the destructive interference effect of the polydimethylsiloxane PDMS dielectric layer and the reflection characteristics of the indium tin oxide ITO transparent conductive thin film layer to achieve an electromagnetic wave absorption rate ≥ 90% in the 6.2–24.6GHz frequency band.

[0019] Beneficial effects

[0020] The beneficial effects of the present invention are as follows: The present invention integrates the dynamic regulation of photoconductive materials, the metasurface structure, and transparent flexible materials into an absorber with an ultra-wide octave bandwidth. The specific effect analysis is as follows:

[0021] 1. Ultra-wide octave broadband absorption performance: Achieve broadband coverage through the frequency-dependent dissipation mechanism of the OPC photoconductive layer and the ITO conductive layer (dominated by OPC at low frequencies and ITO at high frequencies); The PDMS dielectric layer improves the bandwidth by 37% through the λ / 4 destructive interference design (ε = 2.1466, thickness 0.5mm); Make the absorber have an absorption rate exceeding 90% in the 6.2–24.6GHz frequency band, a bandwidth of 18.4GHz, covering the microwave to millimeter-wave frequency bands, significantly superior to the narrowband or fixed frequency band limitations of traditional absorbers.

[0022] 2. Dynamic reconfigurability and real-time response ability: Generate a target light pattern through the DMD micromirror array (415×315, minimum feature size 7.6μm), triggering the resistivity of the OPC layer to drop from 106Ω·cm (dielectric state) to 10 2Ω·cm (conductor state); the synchronization delay with the laser through the FPGA controller is < 50 ns, ensuring precise matching between optical control and conductivity changes. The absorption frequency band is dynamically regulated through DLP projection technology (switching time ≤ 20 μs), supporting real-time calling of several pre-stored patterns to meet the requirements of complex electromagnetic environments.

[0023] 3. Multi-scenario compatibility of transparent flexible design: The ITO thin film (150 nm thick, sheet resistance ≤ 8 Ω / □) has balanced conductivity and transparency; the high flexibility and environmental stability (-40 °C to 80 °C performance stable) of the PDMS layer support complex deployment scenarios; enabling the absorber to have both optical transparency (ITO light transmittance ≥ 85%) and flexible bendability (PDMS substrate), which can conform to curved surfaces (such as UAV shells, smart skins), breaking through the rigidity limitations of traditional metal absorbers.

[0024] 4. High absorption efficiency and wide-angle adaptability: The present invention suppresses interface reflection through gradient impedance matching design (OPC to ITO impedance ratio 10 3 –104), and optimizes energy dissipation; controls the PDMS thickness deviation within ± 5% by controlling the standing wave effect (doping TiO2 nanoparticles) to improve absorption stability; enabling the absorber to have an average absorption rate ≥ 90% within the range of incident angles 0°–60° in TE / TM modes, and the peak absorption rate reaches 95.63%.

[0025] Experimental verification: Modified PDMS expands the bandwidth from 14.2 GHz to 18.4 GHz (a 29.6% increase), and optimizing the ITO thickness (150 nm) balances the absorption rates at high and low frequencies (absorption rate at 6 GHz is 96%, and at 24 GHz is 87%). Description of the Drawings

[0026] Figure 1 is a schematic structural diagram of a reconfigurable absorber for ultra-wide octave broadband absorption based on indium tin oxide (ITO) and photoconductive materials of the present invention;

[0027] Figure 2 is the optical property of the OPC photoconductive thin film with a film thickness of 330 nm;

[0028] Figure 3 is the absorption and reflection spectra of the absorber;

[0029] Figure 4 is the equivalent dielectric constant of the absorber metamaterial equivalent magnetic permeability and equivalent impedance ;

[0030] Figure 5 is the absorption rate spectrum of the absorber at different incident angles, (a) TE mode; (b) TM mode;

[0031] Figure 6 is the average absorption rate of a certain frequency band at different incident angles for the TE / TM mode;

[0032] Description of the reference numerals: 1. Photo-responsive absorbing metasurface, 11. OPC photoconductive layer, 12. Polydimethylsiloxane (PDMS) dielectric layer, 13. Indium tin oxide (ITO) transparent conductive thin film layer, 14. Projection array antenna; 21. Projection lens group, 22. TIR prism, 23. DMD chip, 24. Illumination lens group, 25. 780 nm laser; 3. Vector network analyzer, 31. Horn antenna. Specific embodiments

[0034] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0035] Based on the limitations of the narrow bandwidth and passive fixation of existing traditional absorbers, the present invention provides an absorber with an ultra-wide octave based on a photoconductive material, including a photo-responsive absorbing metasurface and a light driving module capable of projecting different patterns on its surface. By switching the projection pattern, array absorbing units of different sizes are obtained on the photo-responsive absorbing metasurface, and the impedance of the target frequency band is matched by changing the equivalent capacitance / inductance of the absorbing unit structure; the light driving module can project a preset light pattern on the photo-responsive absorbing metasurface, thereby changing the equivalent impedance distribution of the photo-responsive absorbing metasurface; the photo-responsive absorbing metasurface changes the conductivity distribution of the metasurface unit through light control, and adjusts the absorption frequency band in real time, that is, the dynamic adjustment of the absorption performance is realized through non-contact light control.

[0036] Specifically, the photo-responsive absorbing metasurface is a layered structure integrated in the order of an OPC photoconductive layer, a polydimethylsiloxane (PDMS) dielectric layer, and an indium tin oxide (ITO) transparent conductive thin film layer. The OPC photoconductive layer and the indium tin oxide (ITO) transparent conductive thin film layer are coupled through the polydimethylsiloxane (PDMS) dielectric layer to achieve gradient impedance matching, so as to reduce the interface reflection of electromagnetic waves between the OPC photoconductive layer and the indium tin oxide (ITO) transparent conductive thin film layer.

[0037] Specifically, the thickness of the OPC photoconductive layer is 10–20 μm, and under the illumination of a wavelength of 780 nm and a power density ≥5 mW / cm 2 the resistivity drops from 10 6 Ω·cm to 10 2 Ω·cm within a response time of ≤100 μs, and this process realizes temperature stability control through a DLP optical engine equipped with a thermoelectric cooler.

[0038] Specifically, the thickness of the indium tin oxide (ITO) transparent conductive thin film layer is 150 ± 5 nm, the light transmittance in the visible light band of 550 nm is ≥ 85%, the sheet resistance is ≤ 8 Ω / □, and the haze value is ≤ 2%.

[0039] Specifically, the impedance ratio of the OPC photoconductive layer to the indium tin oxide (ITO) transparent conductive thin film layer is 10 3 –104, and a frequency-variable absorption mechanism with a dissipation ratio of 62% of the OPC photoconductive layer at 6.2 GHz and 58% of the OPC photoconductive layer at 24.6 GHz.

[0040] Specifically, the polydimethylsiloxane (PDMS) dielectric layer is doped with 5 wt% titanium dioxide nanoparticles, has a thickness of 0.5 mm, a relative dielectric constant ε = 2.1466, and a loss tangent tanδ = 0.0269. It is set to enable electromagnetic waves to generate λ / 4 wave path interference cancellation in the 6.2 - 24.6 GHz frequency band. After simulation verification, this parameter combination can increase the absorption bandwidth by 37% (compared with the conventional PDMS parameters ε = 2.65, tanδ = 0.01).

[0041] Specifically, the thickness deviation of the polydimethylsiloxane (PDMS) dielectric layer is controlled within ±5% to avoid the decrease in absorption rate caused by the standing wave effect.

[0042] Specifically, the light driving module is a DLP projection module, including a DMD chip, an FPGA controller, and a laser. The DMD chip contains a micromirror array of 415 × 315 with a pitch of 10.8 μm, and the minimum projection feature size is 7.6 μm; the FPGA controller generates a Gray code sequence to control the flipping of the micromirrors, and the pattern switching time is ≤ 20 μs;

[0043] The synchronization delay between the laser and the DMD chip is < 50 ns, and several resonant unit patterns are pre-stored and support real-time calling.

[0044] Specifically, the absorber has an average absorption rate ≥ 90% at an incident angle of 0° - 60° in the TE / TM mode and can conform to the curved surface.

[0045] A method for dynamically regulating electromagnetic waves according to the present invention specifically comprises the following steps:

[0046] Step 1: Project a target light pattern onto the OPC photoconductive layer through the DLP projection module to form a conductive region;

[0047] Step 2: Adjust the size and distribution of the projection pattern to match the equivalent capacitance / inductance of the target frequency band;

[0048] Step 3: Utilize the destructive interference effect of the polydimethylsiloxane (PDMS) dielectric layer and the reflection characteristics of the indium tin oxide (ITO) transparent conductive thin film layer to achieve an electromagnetic wave absorption rate of ≥90% in the frequency band of 6.2 - 24.6 GHz.

[0049] The above technical solution will be further described below with reference to the accompanying drawings:

[0050] In one embodiment, referring to Figure 1 As shown, the present embodiment is a reconfigurable absorber for ultra-wide octave broadband absorption based on indium tin oxide (ITO) and photoconductive materials, mainly composed of an OPC photoconductive layer 11 at the top, a polydimethylsiloxane (PDMS) dielectric layer 12, an indium tin oxide (ITO) transparent conductive thin film layer 13, and a DLP projection module at the bottom. The designed frequency covers the microwave to millimeter wave range. The DLP projection module includes a 780 nm laser 25, an illumination lens group 24, a DMD chip 23, a TIR prism 22, and a projection lens group 21 arranged in sequence along the optical path.

[0051] The OPC photoconductive layer is the core component of the entire electromagnetic surface system. Under the irradiation of a 780 nm wavelength laser, it can achieve the transformation from the dielectric state to the conductor state, and the resistivity rapidly decreases from the original high-resistance state to the value of the conductor state. This transformation quickly "projects" different electromagnetic surface unit structures on the thin film through digital light processing technology (DLP), thereby achieving broadband absorption. Its specific thickness is 330 nm. Referring to Figure 2 As shown, the optical properties of the OPC photoconductive thin film show its excellent light absorption performance at different wavelengths, providing a basis for the efficient operation of the absorber.

[0052] The PDMS (polydimethylsiloxane) layer, as a dielectric layer, has a relative dielectric constant of 2.65 and a loss tangent of 0.01, ensuring good electromagnetic matching performance. The flexible characteristics of PDMS enable the absorber to be arranged on a surface with a certain curvature and maintain the wave absorption performance unchanged. The thickness uniformity and dielectric characteristics of the PDMS layer, referring to Figure 4 shown in (a), play a key role in optimizing the overall wave absorption performance.

[0053] The ITO (indium tin oxide) thin film is a transparent conductive thin film, which not only has conductivity similar to that of a metal but is also transparent to visible light wavelengths, and is considered a key material for constructing an optically transparent broadband absorber. Its thickness is 150 nm. Experiments show that the performance of the ITO thin film in the absorption, reflection, and transmission spectra (as Figure 3 shown) is highly consistent with the simulation data.

[0054] The DLP (Digital Light Processing) module can project different patterns at microsecond time intervals for dynamically switching the wave absorption frequencies of the absorber. Through the DLP module, a periodic array unit can be formed on the surface of the ITO thin film to further enhance the wave absorption effect.

[0055] Preferably, the DLP projection module uses a TIDLPC2607 controller to output a 12-bit LVDS signal to drive the DMD, achieving a synchronization delay of <50 ns with a 780 nm laser, pre-storing a pattern library of 256 resonant unit patterns, and supporting real-time calling of topological structures with different absorption frequency bands.

[0056] Preferably, the DLP projection module uses digital light processing technology (DLP) integrating a DMD chip, adopting a 0.45-inch DLP3000 digital micromirror device, which includes a micromirror array of 415×315 with a pitch of 10.8 μm. The micromirror flipping is controlled by generating a Gray code sequence through an FPGA, and the pattern switching can be completed within ≤20 μs. The minimum feature size of the projection unit is 7.6 μm, corresponding to the electrical size of λ / 40 at the highest operating frequency, which is the basis for achieving broadband absorption in an ultra-wide octave range.

[0057] The working principle of the absorber is based on the multiple reflection and interference effects of electromagnetic waves and the Ohmic loss effect of the material. When electromagnetic waves are incident on the surface of the absorber, the OPC layer and the PDMS layer work together to achieve absorption in different frequency bands. The bottom ITO layer acts as a conductive layer, reflecting electromagnetic waves and forming interference with the incident waves, ultimately achieving broadband absorption.

[0058] In one embodiment, the vector network analyzer 3 uses the electromagnetic simulation software CST to perform simulation analysis on the absorber, and aligns two horn antennas 31 with the optical response wave-absorbing metasurface to be measured. The specific steps are as follows: Set the frequency domain solver, set the boundary conditions in the x and y directions as periodic boundaries, and the z direction as an open boundary; Simulate the absorption of TE mode and TM mode electromagnetic waves in the range of incident angles from 0° to 60°; Analyze the variation of the absorption rate, reflectivity, and transmittance with frequency; The simulation results are as Figure 5 shown. In the TE and TM modes, the absorption rate remains at a relatively high level in the spectra of different incident angles. Especially in the frequency range of 6.2 GHz to 24.6 GHz, the absorption rate exceeds 90%, and the average absorption rate is 95.63%.

[0059] The OPC layer and the ITO layer form a gradient impedance structure: At 6.2 GHz, electromagnetic waves are mainly dissipated by the OPC layer (contribution rate 62%), and at 24.6 GHz, the dissipation ratio of the ITO layer increases to 58%. This frequency-variable dissipation mechanism is the key to achieving an ultra-wide octave range. As Figure 4The equivalent parameter curve shows that there is a cross-resonance point between ε_eff and μ_eff in the 12 - 18 GHz range, resulting in perfect impedance matching.

[0060] If the dielectric constant of PDMS exceeds 3.0 (such as conventional silicone rubber), it will cause impedance mismatch in the high-frequency band, and the measured absorption rate at 24 GHz will drop to 81%; if the thickness of the OPC layer is less than 200 nm, the carrier migration path is incomplete, and the low-frequency absorption rate is reduced by more than 14%.

[0061] In one embodiment, when standard PDMS (ε = 2.65, tanδ = 0.01) is used, the measured -10 dB bandwidth is 14.2 GHz; after using the modified PDMS of the present invention, the bandwidth is extended to 18.4 GHz, with an increase of 29.6%. This data is obtained by actual measurement in a microwave anechoic chamber using a vector network analyzer (VNA).

[0062] In one embodiment, the experimental comparison of the effects of different ITO thicknesses shows that when the thickness increases from 100 nm to 200 nm, the absorption rate at 6 GHz increases from 89% to 96%, but the absorption rate at 24 GHz decreases from 94% to 87%. The particle swarm optimization algorithm determines that 150 nm is the optimal solution.

[0063] The present invention proposes an ultra-octave broadband absorber based on indium tin oxide (ITO) and organic photoconductor materials, which has the characteristics of flexibility, transparency, broadband absorption, and dynamic reconfigurability. Its wave absorption performance is excellent in multiple application scenarios, such as Figure 6 As shown, the average absorption rate of this absorber at different incident angles in the TE / TM mode is higher than 90%. This absorber based on new materials and structures has important application prospects in the fields of radar stealth, electromagnetic compatibility, etc.

[0064] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention.

Claims

1. An absorber with an ultra-wide octave based on a photoconductive material, characterized in that: It includes a light-responsive absorbing metasurface and a light-driven module capable of projecting different patterns on its surface. By switching the projected patterns, array absorbing units of different sizes are obtained on the light-responsive absorbing metasurface. By changing the equivalent capacitance / inductance of the absorbing unit structure, the impedance of the target frequency band is matched. The light-driven module can project a preset light pattern on the light-responsive absorbing metasurface, thereby changing the equivalent impedance distribution of the light-responsive absorbing metasurface. The light-responsive absorbing metasurface changes the conductivity distribution of the metasurface unit through light control, and adjusts the absorbing frequency band in real time, that is, realizes the dynamic adjustment of the absorbing performance through non-contact light control.

2. The absorber with an ultra-wide octave based on a photoconductive material according to claim 1, characterized in that: The light-responsive absorbing metasurface is a layered structure integrated in the order of an OPC photoconductive layer, a polydimethylsiloxane (PDMS) dielectric layer, and an indium tin oxide (ITO) transparent conductive thin film layer. The OPC photoconductive layer and the indium tin oxide (ITO) transparent conductive thin film layer are coupled through the polydimethylsiloxane (PDMS) dielectric layer to achieve gradient impedance matching, so as to reduce the interface reflection of electromagnetic waves between the OPC photoconductive layer and the indium tin oxide (ITO) transparent conductive thin film layer.

3. The absorber with an ultra-wide octave based on a photoconductive material according to claim 2, characterized in that: The thickness of the OPC photoconductive layer is 10–20 μm. Under illumination at a wavelength of 780 nm and a power density ≥5 mW / cm 2 , the resistivity decreases from 106 Ω·cm to 10 2 Ω·cm, and the response time ≤100 μs.

4. The absorber with an ultra-wide octave based on a photoconductive material according to claim 3, wherein: The thickness of the indium tin oxide (ITO) transparent conductive thin film layer is 150 ± 5 nm, the light transmittance in the 550 nm visible light band is ≥ 85%, the sheet resistance is ≤ 8 Ω / □, and the haze value is ≤ 2%.

5. The absorber with an ultra-wide octave based on a photoconductive material according to claim 4, characterized in that: The impedance ratio of the OPC photoconductive layer to the indium tin oxide (ITO) transparent conductive thin film layer is 10 3 –104, and the frequency-variable absorption mechanism in which the dissipation ratio of the OPC photoconductive layer is 62% at 6.2 GHz and 58% at 24.6 GHz.

6. The oversized octave absorber based on a photoconductive material according to claim 5, wherein: The polydimethylsiloxane (PDMS) dielectric layer is doped with 5 wt% titanium dioxide nanoparticles, the thickness is 0.5 mm, the relative dielectric constant ε = 2.1466, and the loss tangent tanδ = 0.0269.

7. The absorber with an ultra-wide octave based on a photoconductive material according to claim 6, wherein: The thickness deviation of the polydimethylsiloxane (PDMS) dielectric layer is controlled within ±5% to avoid the decrease in absorption rate caused by the standing wave effect.

8. The absorber with an ultra-wide octave based on a photoconductive material according to claim 1, wherein: The light-driven module is a DLP projection module, including a DMD chip, an FPGA controller, and a laser. The DMD chip contains a micromirror array of 415 × 315 with a pitch of 10.8 μm, and the minimum projection feature size is 7.6 μm. The FPGA controller generates a Gray code sequence to control the flipping of the micromirrors, and the pattern switching time is ≤ 20 μs. The synchronization delay between the laser and the DMD chip is < 50 ns, and several resonant unit patterns are pre-stored and support real-time calling.

9. The absorber with an ultra-wide octave based on a photoconductive material according to claim 1, characterized in that: When the absorber is in the TE / TM mode, the average absorption rate is ≥ 90% when the incident angle is 0° to 60°, and it can fit the curved surface.

10. A method for dynamically regulating electromagnetic waves, based on the ultra-wide octave absorber based on photoconductive materials according to any one of claims 1-9; characterized in that The specific steps are as follows: Project a target light pattern onto the OPC photoconductive layer through the DLP projection module to form a conductive region. Adjust the size and distribution of the projected pattern to match the equivalent capacitance / inductance of the target frequency band. Utilize the interference cancellation effect of the polydimethylsiloxane (PDMS) dielectric layer and the reflection characteristics of the indium tin oxide (ITO) transparent conductive thin film layer to achieve an electromagnetic wave absorption rate of ≥ 90% in the 6.2–24.6 GHz frequency band.

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