Perovskite-based all-stokes polarized photodetector and preparation method thereof

Abstract

The application discloses a kind of perovskite-based full stokes polarized photoelectric detector and preparation method thereof, belong to photoelectric detector technical field, including glass substrate, transparent conductive layer, perovskite hypersurface structure layer and metal electrode structure, glass substrate is provided with transparent conductive layer, transparent conductive layer is provided with perovskite hypersurface structure layer, perovskite hypersurface structure layer is provided with metal electrode structure, perovskite hypersurface structure layer at least includes four functional areas, four functional areas are reference area, first hypersurface array, second hypersurface array and third hypersurface array respectively, metal electrode structure at least includes four metal electrode units, four metal electrode units are distributed in the four around functional areas in symmetrical mode, and form central light response area by surrounding.This application can realize different polarization state incident light to generate differential photoelectric response, to realize the synchronous acquisition of full stokes parameter on single device platform.

Description

Technical Field

[0001] This invention relates to the field of photodetector technology, specifically to a perovskite-based all-Stokes polarization photodetector and its fabrication method. Background Technology

[0002] Photodetectors, as crucial devices for acquiring and converting photoelectric information, have wide applications in optical communication, polarization imaging, environmental monitoring, and information security. With increasing application demands, traditional detection methods relying solely on light intensity information are insufficient for complex application scenarios. In contrast, light polarization information provides richer physical characteristics, with the full Stokes parameter completely describing the polarization state of light. Therefore, achieving the detection of the full Stokes parameter is of great significance.

[0003] Currently, all-Stokes polarization detection typically relies on multiple detector units combined with devices such as polarizers and waveplates for step-by-step measurements. This not only results in complex structures and large sizes but also makes on-chip integration difficult. Furthermore, multi-channel measurements are prone to introducing systematic errors, limiting their application in miniaturized and highly integrated optoelectronic systems.

[0004] To achieve polarization-selective response, existing research has attempted to manipulate incident light using artificial micro / nano structures. For example, patent CN101852884A discloses a double-helix metal wire grid circular polarizer, which achieves selective transmission of circularly polarized light by constructing a three-dimensional helical microstructure; patent CN114265140A discloses a metasurface circular polarization device, which achieves effective manipulation of circularly polarized light based on a two-dimensional chiral metasurface structure. Although the above methods have made some progress in the detection of specific polarization states (such as circularly polarized light), their functionality is usually limited to a single or a few polarization components, making it difficult to achieve comprehensive detection of light with arbitrary polarization states, and especially unable to directly obtain complete Stokes parameter information.

[0005] On the other hand, organic-inorganic hybrid halide perovskite materials have attracted widespread attention in the field of photoelectric detection due to their high absorption coefficient, long carrier diffusion length, and excellent photoelectric conversion performance. Furthermore, perovskite materials offer advantages such as solution-based preparation, low cost, and ease of fabrication into micro / nano structures, providing a solid foundation for their integration with metasurface structures. However, existing perovskite photodetectors mostly employ uniform thin-film structures, lacking selective response to different polarization states, making it difficult to achieve effective decoupling and measurement of polarization information.

[0006] Therefore, how to construct a photodetector that is simple in structure, easy to fabricate, and capable of achieving independent responses of multiple polarization components in a single device, thereby realizing full Stokes parameter measurement, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address this issue, the present invention provides a perovskite-based all-Stokes polarization photodetector and its fabrication method, thereby solving the problem in the prior art where polarization detectors are limited to a single or a few polarization components, making it difficult to achieve comprehensive detection of light in any polarization state.

[0008] To achieve the above objectives, the present invention provides the following technical solution: According to a first aspect of the present invention, a perovskite-based all-Stokes polarization photodetector is provided, comprising a glass substrate, a transparent conductive layer, a perovskite metasurface structure layer, and a metal electrode structure. The transparent conductive layer is disposed on the glass substrate, the perovskite metasurface structure layer is disposed on the transparent conductive layer, and the metal electrode structure is disposed on the perovskite metasurface structure layer. The perovskite metasurface structure layer includes at least four functional regions, namely a reference region, a first metasurface array, a second metasurface array, and a third metasurface array. The reference region is a planar perovskite region without micro / nano structures, and the first, second, and third metasurface arrays are planar perovskite regions composed of micro / nano structures. The metal electrode structure includes at least four metal electrode units, which are symmetrically distributed around the functional regions and enclose a central photoresponse region.

[0009] Furthermore, the metal electrode structure is a composite metal structure, comprising a chromium adhesion layer and a gold conductive layer, wherein the thickness of the chromium in the composite metal structure is 5-10 nm and the thickness of the gold is 30-50 nm.

[0010] Furthermore, the photodetector has a length of 25-35 μm and a width of 25-35 μm; the perovskite metasurface structure layer has a thickness of 300-500 nm; the transparent conductive layer has a thickness of 100-200 nm; and the perovskite metasurface structure layer has a lattice period of 1000-1500 nm.

[0011] Furthermore, the micro / nano structures on the first, second, and third metasurface arrays are elliptical hole structures. The elliptical holes are periodically arranged in an array within a planar perovskite region. The elliptical hole structure is a 6×6 arranged cell structure. The elliptical hole has a major axis and a minor axis, with the major axis dimension being 300-600 nm and the minor axis dimension being 200-400 nm. The angle between the major axis of the elliptical hole and the reference coordinate axis is a rotation angle θ, and the rotation angle θ ranges from [-90°, 90°]. The depth of the elliptical hole is 350-450 nm.

[0012] According to a second aspect of the present invention, a method for fabricating a perovskite-based all-Stokes polarization photodetector is provided, for fabricating the perovskite-based all-Stokes polarization photodetector as described in any of the preceding claims, comprising the following steps: Step S1: Perform ultrasonic cleaning on the glass substrate; Step S2: Dry the glass substrate after ultrasonic cleaning; Step S3: Deposit an ITO conductive film on the surface of the dried glass substrate using magnetron sputtering to obtain a glass substrate covered with a transparent conductive layer; Step S4: Prepare a perovskite precursor solution film on the transparent conductive layer, so that it is in a wet state of incomplete crystallization; Step S5: Design the photolithographic masks corresponding to the first metasurface array, the second metasurface array, and the third metasurface array; Step S6: A metasurface micro / nano structure array is constructed on the incompletely crystallized perovskite precursor solution film in step S4 by nanoimprinting, and crystallization is completed during the imprinting process. The metasurface micro / nano structure array is constructed according to the photolithographic mask designed in step S5, and a glass substrate covered with a perovskite metasurface structure layer and a transparent conductive layer is obtained. Step S7: Prepare a metal electrode structure on the perovskite metasurface structure layer of step S6 to obtain a glass substrate covered with a metal electrode structure, a perovskite metasurface structure layer and a transparent conductive layer.

[0013] Furthermore, step S1 specifically includes: immersing the glass substrate in deionized water, acetone solution, and anhydrous ethanol solution in sequence for ultrasonic cleaning for 5-10 minutes each; Step S2 specifically includes: drying the glass substrate after ultrasonic cleaning with nitrogen gas, and heating and drying it at 60-100℃ for 5-15 minutes.

[0014] Furthermore, step S3 specifically includes: placing the dried glass substrate into the vacuum chamber of the magnetron sputtering equipment and evacuating it to a vacuum level of 5 × 10⁻⁶. -4 With a substrate vacuum level below Pa, argon gas is introduced as the working gas and the pressure is adjusted to 0.3-1.0 Pa. ITO target material is sputtered and deposited under sputtering power conditions of 50-150 W to form an ITO conductive film on the surface of the glass substrate. The thickness of the ITO conductive film is 100-200 nm.

[0015] Furthermore, step S4 specifically includes: placing a glass substrate with a transparent conductive layer in a spin coating device, dropping a perovskite precursor solution onto its surface and spin coating it to form a film, and adding an anti-solvent, chlorobenzene, during the spin coating process to promote rapid nucleation of the film and form a uniform perovskite precursor solution film.

[0016] Furthermore, step S6 specifically includes: Step S601: Select a silicon wafer as the substrate, clean it with Piranha solution to remove organic contaminants, rinse it with deionized water and then dry it; Step S602: Spin-coat electron beam photoresist onto the dried silicon wafer surface. After pre-baking, use electron beam lithography to expose and develop the pattern of the photomask designed in step S5. Transfer the pattern to the silicon wafer through reactive ion etching to form a silicon master mold. Then, form an anti-adhesion layer on its surface by OTS vapor deposition. Step S603: Spin-coat UV-curable template adhesive onto the anti-adhesion layer on the surface of the silicon master mold, cover with PET film, cure by UV irradiation, and peel off to obtain a flexible nanoimprint mold with an inverse structure; Step S604: Cover the surface of the incompletely crystallized perovskite precursor solution film with the flexible nanoimprint mold, and imprint for 10 minutes at a temperature of 100°C and a pressure of 2.2MPa to allow the perovskite to complete structural replication and crystallization. Step S605: Slowly release the pressure, cool to room temperature, and then peel off the flexible nanoimprint mold to obtain a perovskite metasurface structure layer with micro-nano structure.

[0017] Furthermore, step S7 specifically includes: Step S701: Design a metal mask template, which has four symmetrically distributed electrode patterns. The positions of the four electrode patterns correspond to the electrode deposition areas around the perovskite metasurface structure layer. Step S702: Place the glass substrate covered with the perovskite metasurface structure layer and the transparent conductive layer on the sample stage of the thermal evaporation equipment, and tightly attach the metal mask above the surface of the perovskite metasurface structure layer or directly cover the surface of the perovskite metasurface structure layer, ensuring that the four patterns are aligned with the corresponding positions around the perimeter of the perovskite metasurface structure layer. Step S703: Evacuate the thermal evaporation equipment to a pressure below 5×10 -4 Pa is thermally deposited using chromium and gold as evaporation sources in sequence. The chromium layer has a thickness of 5-10 nm and serves as an adhesion layer. The gold layer has a thickness of 30-50 nm and serves as a conductive layer. Step S704: After the vapor deposition is completed, the glass substrate covered with the perovskite metasurface structure layer and the transparent conductive layer is removed from the thermal vapor deposition equipment, and the metal mask is peeled off. Four metal electrode units are symmetrically formed around the perovskite metasurface structure layer, and the four metal electrode units enclose the central photoresponse region. Step S705: The glass substrate with four symmetrically distributed metal electrode units obtained in step S704 is cleaned with nitrogen gas to obtain a fully Stokes polarized photodetector covered with a metal electrode structure.

[0018] The present invention has the following advantages: This invention integrates multiple metasurface arrays with different polarization modulation functions into a perovskite metasurface structure layer, enabling the device to generate differentiated photoelectric responses to incident light with different polarization states. This allows for the simultaneous acquisition of all Stokes parameters on a single device platform, significantly improving the device's functional integration and information acquisition efficiency. Simultaneously, nanoimprinting technology is used to simultaneously construct micro / nano structures during the perovskite thin film crystallization process, simplifying the fabrication process, reducing costs, and making it suitable for large-area fabrication. Furthermore, by setting a reference region and the metasurface array, the comparison between the incident light intensity signal and the polarization response signal is achieved, which helps improve the accuracy and stability of polarization detection. Therefore, this invention has advantages such as simple structure, ease of fabrication, and high integration, and can be applied to polarization imaging, optical communication, and biosensing. Attached Figure Description

[0019] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0020] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0021] Figure 1 This is a schematic diagram of the structure of the photodetector provided in Embodiment 1 of the present invention; Figure 2 This is a top view of the photodetector provided in Embodiment 1 of the present invention; Figure 3 A schematic diagram of the absorption rates of the photodetector provided in Embodiment 1 of the present invention under TE and TM polarization under near-infrared light irradiation with wavelengths of 1850-2050nm. Figure 4A schematic diagram of the absorption rate of the photodetector provided in Embodiment 1 of the present invention under near-infrared light illumination with wavelengths of 1850-2050nm and linear polarization at 45° and 135°. Figure 5 A schematic diagram of the absorption rates of LCP and RCP circularly polarized photodetectors provided in Embodiment 1 of the present invention under near-infrared light irradiation at wavelengths of 1850-2050 nm. Figure 6 This is a schematic diagram of the surface structure of the metasurface array provided in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram showing the absorption rate of the photodetector provided in Comparative Example 1 of the present invention under near-infrared light illumination at wavelengths of 1850-2050 nm with linear polarization at 45° and 135°.

[0022] In the picture: 1 Glass substrate; 2 Transparent conductive layer; 3 Perovskite metasurface structure layer; 4 First metasurface array; 5 Second metasurface array; 6 Third metasurface array; 7 Metal electrode structure. Detailed Implementation

[0023] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 This embodiment provides a perovskite-based all-Stokes polarization photodetector, such as... Figure 1 and Figure 2 As shown, the structure includes a glass substrate 1, a transparent conductive layer 2, a perovskite metasurface structure layer 3, and a metal electrode structure 7. The transparent conductive layer 2 is disposed on the glass substrate 1, the perovskite metasurface structure layer 3 is disposed on the transparent conductive layer 2, and the metal electrode structure 7 is disposed on the perovskite metasurface structure layer 3. The perovskite metasurface structure layer 3 includes at least four functional regions, namely a reference region, a first metasurface array 4, a second metasurface array 5, and a third metasurface array 6. The reference region is a planar perovskite region without micro / nano structures. The first metasurface array 4, the second metasurface array 5, and the third metasurface array 6 are planar perovskite regions composed of micro / nano structures. The metal electrode structure 7 includes at least four metal electrode units, which are symmetrically distributed around the functional regions, forming electrical contact with the perovskite metasurface structure layer 3 and enclosing a central photoresponse region.

[0025] The metal electrode structure 7 is a composite metal structure, comprising a chromium adhesion layer and a gold conductive layer. The thickness of the chromium layer in the composite metal structure is 5-10 nm, and the thickness of the gold layer is 30-50 nm. Preferably, the thickness of the chromium layer is 5 nm, and the thickness of the gold layer is 40 nm.

[0026] The photodetector has a length of 25-35 μm and a width of 25-35 μm; the thickness of the perovskite metasurface structure layer 3 is 300-500 nm; the thickness of the transparent conductive layer 2 is 100-200 nm; and the lattice period of the perovskite metasurface structure layer 3 is 1000-1500 nm.

[0027] The micro / nano structures on the first metasurface array 4, the second metasurface array 5, and the third metasurface array 6 are elliptical hole structures. The elliptical holes are periodically arranged in an array within the planar perovskite region. The elliptical hole structure is a 6×6 arranged cell structure. The elliptical holes have a major axis and a minor axis. The major axis has a size of 300-600 nm, and the minor axis has a size of 200-400 nm. The angle between the major axis of the elliptical hole and the reference coordinate axis is a rotation angle θ, and the value of the rotation angle θ is in the range of [-90°, 90°]. The depth of the elliptical holes is 350-450 nm.

[0028] The size of the micro / nano structures of the first metasurface array 4, the second metasurface array 5, and the third metasurface array 6 is adjusted according to the target detection wavelength and polarization state.

[0029] The specific structural designs of the first metasurface array 4, the second metasurface array 5, and the third metasurface array 6 are as follows: The first metasurface array 4 is an elliptical aperture array, containing 6×6 cells arranged in a uniformly spaced manner; the major semi-axis of the elliptical aperture is 500nm, the minor semi-axis is 400nm, the lattice period is 1360nm, and the depth of the elliptical aperture is 430nm; the rotation angle θ of the major axis of the elliptical aperture relative to the reference coordinate axis is 0°.

[0030] The second metasurface array 5 is an elliptical aperture array with a specific orientation angle, containing 6×6 cells arranged at uniform intervals; the major semi-axis of the elliptical aperture is 500nm, the minor semi-axis is 400nm, the lattice period is 1360nm, and the depth of the elliptical aperture is 430nm; the rotation angle θ of the major axis of the elliptical aperture relative to the reference coordinate axis is 45°.

[0031] The third metasurface array 6 is a composite array composed of elliptical holes of different sizes and orientation angles, containing 6×6 cells arranged in a uniformly spaced manner; wherein, the semi-major axis of the small-sized elliptical hole is 300nm and the semi-minor axis is 200nm, the semi-major axis of the large-sized elliptical hole is 500nm and the semi-minor axis is 250nm, the lattice period is 1300nm, and the depth of the elliptical hole is 430nm; the rotation angle θ of the major axis of the large-sized elliptical hole is 30°, and the rotation angle θ of the major axis of the small-sized elliptical hole is -40°.

[0032] The overall dimensions of the perovskite-based all-Stokes polarization photodetector are: length 25-35μm, width 25-35μm, thickness of transparent conductive layer 2 100-200nm, and thickness of perovskite metasurface structure layer 3 300-500nm.

[0033] Preferably, the specific dimensions of the all-Stokes polarization photodetector provided by the present invention are designed as follows: the overall length of the device is 30 μm, the width is 30 μm, the thickness of the transparent conductive layer 2 is 180 nm, and the thickness of the perovskite metasurface structure layer 3 is 450 nm.

[0034] When light of a specific polarization state is incident on any metasurface array, the local field enhancement effect will be generated due to its modulation of the electromagnetic field. This will lead to enhanced light absorption in the perovskite metasurface structure layer 3 and different distributions of photogenerated carriers. Different types of metasurface arrays correspond to different polarization components. Specifically, the first metasurface array 4 corresponds to the TE / TM polarization component, the second metasurface array 5 corresponds to the ±45° linear polarization component, and the third metasurface array 6 corresponds to the LCP / RCP circular polarization component. In addition, the region without metasurface structure is used to provide a total light intensity reference signal, which corresponds to the Stokes parameters S0, S1, S2, and S3, respectively.

[0035] The perovskite metasurface-based polarization photodetector provided in this application can achieve full Stokes parameter detection of incident light with arbitrary polarization states. Compared with existing technical solutions that rely on the combination of multi-level polarization modulation elements (such as polarizers, waveplates, etc.) to achieve polarization analysis, this invention integrates multiple functional metasurface structures in a single device, realizing parallel decoupling and synchronous detection of different polarization components, thereby significantly improving system integration and reducing device complexity. At the same time, by adjusting the geometric dimensions, periodic parameters, and orientation characteristics of the metasurface structure, flexible adaptation to different operating wavelength ranges can be achieved, enhancing the applicability of the device in multi-band polarization detection.

[0036] This embodiment also provides a method for fabricating a perovskite-based all-Stokes polarization photodetector, comprising the following steps: Step S1: Place the glass substrate into deionized water, acetone solution and anhydrous ethanol solution in turn and perform ultrasonic cleaning for 5-10 minutes each; Step S2: Dry the ultrasonically cleaned glass substrate with nitrogen gas and heat it at 60-100℃ for 5-15 minutes. Step S3: Deposit an ITO conductive film on the surface of the dried glass substrate using magnetron sputtering to obtain a glass substrate covered with a transparent conductive layer; Specifically, the dried glass substrate is placed inside the vacuum chamber of the magnetron sputtering equipment, and the vacuum level is evacuated to 5 × 10⁻⁶. - 4 With a substrate vacuum of less than Pa, argon gas is introduced as the working gas and the pressure is adjusted to 0.3-1.0 Pa. ITO target material is sputtered and deposited under sputtering power of 50-150 W to form an ITO conductive film on the surface of the glass substrate. The thickness of the ITO conductive film is 100-200 nm. Step S4: Prepare a perovskite precursor solution film on the transparent conductive layer, so that it is in a wet state of incomplete crystallization; Specifically, a perovskite precursor solution was prepared by heating and stirring a mixed solvent of 1.2 mmol lead iodide (553.2 mg) and 1.2 mmol dimethyl sulfoxide (190 mg) at a volume ratio of 9:1 at 70°C for 8 hours. A glass substrate with a transparent conductive layer was placed in a spin-coating apparatus, and the perovskite precursor solution was dropped onto its surface and spin-coated at 3000 rpm for 10 seconds. During the spin-coating process, the anti-solvent chlorobenzene was added dropwise to promote rapid nucleation and the formation of a uniform perovskite precursor solution film.

[0037] Step S5: Design the photolithographic masks corresponding to the first metasurface array, the second metasurface array, and the third metasurface array; Specifically, in electromagnetic simulation software, multiple functional regions are constructed by adjusting the geometric dimensions, periodic parameters, and orientation angles of micro- and nano-structures, including a reference region, a first metasurface array, a second metasurface array, and a third metasurface array. The reference region is a planar perovskite region without micro / nano structures, which has a basically consistent optical response to incident light of different polarization states and is used to provide a reference signal for the intensity of the incident light. The first metasurface array, the second metasurface array, and the third metasurface array are planar perovskite regions composed of micro / nano structures. The first metasurface array, the second metasurface array, and the third metasurface array are used to generate differentiated responses to incident light of different polarization states. The corresponding photolithographic mask is designed according to the structural parameters of each functional region.

[0038] Step S6: A metasurface micro / nano structure array is constructed on the incompletely crystallized perovskite precursor solution film in step S4 using a nanoimprinting method, and crystallization is completed during the imprinting process. The metasurface micro / nano structure array is constructed according to the photolithographic mask designed in step S5, resulting in a glass substrate covered with a perovskite metasurface structure layer and a transparent conductive layer. Step S7: Prepare a metal electrode structure on the perovskite metasurface structure layer in step S6 to obtain a glass substrate covered with a metal electrode structure, a perovskite metasurface structure layer and a transparent conductive layer.

[0039] Step S6 specifically includes: Step S601: Select a silicon wafer as the substrate, clean it with Piranha solution to remove organic contaminants, rinse it with deionized water and then dry it; Step S602: Spin-coat electron beam photoresist onto the dried silicon wafer surface. After pre-baking, use electron beam lithography to expose and develop the pattern of the photomask designed in step S5. Transfer the pattern to the silicon wafer through reactive ion etching to form a silicon master mold. Then, form an anti-adhesion layer on its surface by OTS vapor deposition. Step S603: Spin-coat UV-curable template adhesive onto the anti-adhesion layer on the surface of the silicon master mold, cover with PET film, cure by UV irradiation, and peel off to obtain a flexible nanoimprint mold with an inverse structure; Step S604: A flexible nanoimprint mold is covered on the surface of the incompletely crystallized perovskite precursor solution film, and imprinted for 10 minutes at a temperature of 100°C and a pressure of 2.2MPa to allow the perovskite to complete structural replication and crystallization. Step S605: Slowly release the pressure, cool to room temperature, and then peel off the flexible nanoimprint mold to obtain a perovskite metasurface structure layer with micro-nano structure.

[0040] Step S7 specifically includes: Step S701: Design a metal mask template with four symmetrically distributed electrode patterns. The positions of the four electrode patterns correspond to the electrode deposition areas around the perovskite metasurface structure layer. Step S702: Place the glass substrate covered with the perovskite metasurface structure layer and the transparent conductive layer on the sample stage of the thermal evaporation equipment, and tightly attach the metal mask above the surface of the perovskite metasurface structure layer or directly cover the surface of the perovskite metasurface structure layer, ensuring that the four patterns are aligned with the corresponding positions around the perimeter of the perovskite metasurface structure layer. Step S703: Evacuate the thermal evaporation equipment to a pressure below 5×10 -4 Pa is thermally deposited using chromium and gold as evaporation sources in sequence. The chromium layer has a thickness of 5-10 nm and serves as an adhesion layer. The gold layer has a thickness of 30-50 nm and serves as a conductive layer. Step S704: After the vapor deposition is completed, the glass substrate covered with the perovskite metasurface structure layer and the transparent conductive layer is removed from the thermal vapor deposition equipment, and the metal mask is peeled off. Four metal electrode units are symmetrically formed around the perovskite metasurface structure layer, and the four metal electrode units enclose the central photoresponse region. Step S705: The glass substrate with four symmetrically distributed metal electrode units obtained in step S704 is cleaned with nitrogen gas to obtain a fully Stokes polarized photodetector covered with a metal electrode structure.

[0041] To verify the beneficial effects of this embodiment, the following simulation analysis was conducted: Numerical simulations of near-infrared light with a wavelength of 1910 nm were performed using electromagnetic simulation software. Under the same structural parameters and incident conditions, the optical absorption response of the device was calculated for TE-polarized light and TM-polarized light incident light, respectively. Figure 3 As shown, in the near-infrared region at 1910 nm, the device absorbs approximately 75% of TE-polarized light and approximately 26% of TM-polarized light, with a difference of 49% and a corresponding polarization extinction ratio of approximately 4.60 dB. Furthermore, throughout the 1850-2050 nm wavelength range, the TE and TM polarization absorption spectra maintain a clear separation trend without any overlap, indicating that the device possesses stable anisotropic optical response characteristics.

[0042] The above results demonstrate that this structure can effectively distinguish between TE (horizontal) and TM (vertical) polarization components, providing a reliable basis for the extraction of horizontal and vertical linear polarization components (S1 parameters).

[0043] Under the same simulation parameters, linearly polarized incident light with polarization angles of 45° and 135° (i.e., -45°) was simulated and analyzed. For example... Figure 4 As shown, at the target wavelength of 1910nm near-infrared light, the device has an absorption rate of about 28% for 45° linearly polarized light and about 76% for 135° linearly polarized light. The response difference between the two is about 48%, and the corresponding polarization contrast reaches 46.2%.

[0044] Further analysis revealed that the response curves of the two diagonal polarization states were clearly separated and exhibited different trends throughout the entire operating wavelength range, indicating that the metasurface structure has significant directional sensitivity to diagonal polarization.

[0045] Therefore, this device can effectively decouple and identify the ±45° linear polarization components (S2 parameters).

[0046] Numerical simulations were performed on the incident conditions of LCP (left-handed circularly polarized light) and RCP (right-handed circularly polarized light) under the same simulation parameters. For example...Figure 5 As shown, at the near-infrared wavelength of 1910 nm, the device exhibits approximately 85% absorption of left-handed circularly polarized light and approximately 55% absorption of right-handed circularly polarized light, with an absorption difference of 30%, corresponding to a circular dichroism (CD) of approximately 0.214. Furthermore, throughout the entire operating wavelength range, the response curves of LCP and RCP show a significant asymmetric distribution, indicating that the structure possesses a remarkable chiral optical response capability.

[0047] The results demonstrate that the device can effectively distinguish between left-handed and right-handed circular polarization components, thereby enabling the detection of circular polarization information (S3 parameters).

[0048] Example 2 Based on Example 1, the structural units of the first metasurface array, the second metasurface array, and the third metasurface array can also be designed as an "L"-shaped structure, such as... Figure 6 The diagram shows the unit structure and related dimensional parameters. The geometric parameters of the "L"-shaped structural unit include the unit period P, the horizontal structural length D, the vertical structural height H, and the structural linewidth parameters K and W. K represents the width of the upper horizontal strip of the vertical portion, and W represents the height of the right vertical strip of the horizontal portion.

[0049] Specifically, the "L"-shaped structure consists of a vertical strip and a horizontal strip connected to each other at right angles. By adjusting the horizontal structural length D, the vertical structural height H, and the structural linewidth parameters K and W, precise control over the local electromagnetic field distribution and light absorption characteristics of the structure can be achieved.

[0050] The first, second, and third metasurface arrays employ "L"-shaped structural units with different orientations. By adjusting their geometric dimensions and arrangement, selective coupling and differentiated responses to incident light with different polarization states can be achieved, thereby enabling the decoupling and extraction of polarization information. The relevant dimensional parameters of the "L"-shaped structural units are shown in the table below.

[0051] Dimensional parameters of the “L” shaped structural unit

[0052] Through COMSOL electromagnetic simulation analysis, it was found that the "L"-shaped structural unit can excite local resonant modes under specific structural parameter conditions and produce differentiated absorption responses to incident light with different polarization states. By adjusting parameters P, D, H, K, and W, the polarization selectivity and response intensity of the device can be synergistically controlled, thereby improving the ability to identify each polarization component and achieving effective acquisition of all Stokes parameters.

[0053] Comparative Example 1 Based on Example 1, the second metasurface array was removed, retaining only the first and third metasurface arrays. Electromagnetic simulation software was used to analyze incident light with different polarization states. Under the same simulation conditions, the device's response characteristics to TE / TM polarized light, ±45° linearly polarized light, and left-handed / right-handed circularly polarized light were calculated. The device still exhibits differentiated responses to the TE / TM polarization component and the circularly polarized component, but due to the lack of the second metasurface array, such as... Figure 7 As shown, the device's response to ±45° linear polarization components is significantly reduced, making it unable to effectively decouple diagonal linear polarization information.

[0054] Therefore, this structure cannot fully acquire all polarization information of the incident light, making it difficult to accurately characterize the full Stokes parameters. In contrast, this invention, by setting up multiple sets of functionally complementary metasurface arrays, achieves independent response and collaborative resolution of different polarization components, thus possessing complete polarization information detection capabilities.

[0055] Comparative Example 2 Based on Example 1, all metasurface array structures were removed, leaving only the reference region without micro / nano structures. Under the same simulation conditions, incident light with different polarization states was simulated and analyzed. The absorbance of the photodetector under near-infrared light illumination at wavelengths of 1850-2050 nm was calculated for TE and TM polarization, 45° and 135° linear polarization, and LCP and RCP circular polarization. The absorbance consistently varied between 0.25 and 0.15, with consistent curves. Therefore, the device's light absorption response to incident light with different polarization states was essentially consistent, exhibiting no significant polarization selectivity.

[0056] Therefore, this structure cannot distinguish between different polarization components and can only provide incident light intensity information, failing to achieve polarization state resolution. In contrast, this invention introduces a metasurface structure with anisotropic response characteristics, enabling the device to produce differentiated responses to incident light with different polarization states, thereby achieving effective identification of polarization information.

[0057] Comparative Example 3 Based on Example 1, the perovskite light-absorbing layer was removed, leaving only the metasurface structure. Analysis under the same simulation and testing conditions revealed that although the metasurface structure could still exert some electromagnetic field modulation on the incident light, the device could not generate a stable photoelectric response signal due to the lack of an effective light absorption and carrier generation mechanism.

[0058] Therefore, this structure makes it difficult to effectively detect polarized light signals. In contrast, this invention uses perovskite material as the light-absorbing layer, which not only enables efficient generation of photogenerated carriers but also works synergistically with the metasurface structure to achieve effective conversion of polarization information into electrical signals.

[0059] The perovskite metasurface-based all-Stokes polarization photodetector provided by this invention achieves selective modulation and synergistic response to different polarization components by integrating multiple functional metasurface arrays in a single device, thereby enabling complete detection of all Stokes parameters for incident light of any polarization state; at the same time, the perovskite material has both excellent light absorption characteristics and carrier transport performance, enabling the device to have good signal output capability while ensuring high responsivity.

[0060] Furthermore, this invention can achieve polarization information analysis without introducing additional optical components such as polarizers or waveplates, which significantly reduces system complexity and improves integration. By adjusting the geometric dimensions and arrangement parameters of the metasurface structure units, it can also achieve flexible adaptation to different operating wavelength ranges, thereby expanding the application potential of the device in the field of multi-band polarization detection.

[0061] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A perovskite-based all-Stokes polarization photodetector, characterized in that, The device includes a glass substrate, a transparent conductive layer, a perovskite metasurface structure layer, and a metal electrode structure. The transparent conductive layer is disposed on the glass substrate, the perovskite metasurface structure layer is disposed on the transparent conductive layer, and the metal electrode structure is disposed on the perovskite metasurface structure layer. The perovskite metasurface structure layer includes at least four functional regions, namely a reference region, a first metasurface array, a second metasurface array, and a third metasurface array. The reference region is a planar perovskite region without micro / nano structures. The first, second, and third metasurface arrays are planar perovskite regions composed of micro / nano structures. The metal electrode structure includes at least four metal electrode units, which are symmetrically distributed around the functional regions and enclose a central photoresponse region. The micro / nano structures on the first, second, and third metasurface arrays are elliptical hole structures. The elliptical holes are periodically arranged in an array within a planar perovskite region. The elliptical hole structure is a 6×6 arranged cell structure. The elliptical holes have a major axis and a minor axis. The major axis has a size of 300-600 nm, and the minor axis has a size of 200-400 nm. The angle between the major axis of the elliptical hole and the reference coordinate axis is a rotation angle θ, and the rotation angle θ ranges from -90° to 90°. The depth of the elliptical holes is 350-450 nm.

2. The perovskite-based all-Stokes polarization photodetector as described in claim 1, characterized in that, The metal electrode structure is a composite metal structure, comprising a chromium adhesion layer and a gold conductive layer, wherein the thickness of the chromium in the composite metal structure is 5-10 nm and the thickness of the gold is 30-50 nm.

3. The perovskite-based all-Stokes polarization photodetector as described in claim 1, characterized in that, The photodetector has a length of 25-35 μm and a width of 25-35 μm; the perovskite metasurface structure layer has a thickness of 300-500 nm; the transparent conductive layer has a thickness of 100-200 nm; and the perovskite metasurface structure layer has a lattice period of 1000-1500 nm.

4. A method for fabricating a perovskite-based all-Stokes polarization photodetector, used to fabricate the perovskite-based all-Stokes polarization photodetector as described in any one of claims 1-3, characterized in that, Includes the following steps: Step S1: Perform ultrasonic cleaning on the glass substrate; Step S2: Dry the glass substrate after ultrasonic cleaning; Step S3: Deposit an ITO conductive film on the surface of the dried glass substrate using magnetron sputtering to obtain a glass substrate covered with a transparent conductive layer; Step S4: Prepare a perovskite precursor solution film on the transparent conductive layer, so that it is in a wet state of incomplete crystallization; Step S5: Design the photolithographic masks corresponding to the first metasurface array, the second metasurface array, and the third metasurface array; Step S6: A metasurface micro / nano structure array is constructed on the incompletely crystallized perovskite precursor solution film in step S4 by nanoimprinting, and crystallization is completed during the imprinting process. The metasurface micro / nano structure array is constructed according to the photolithographic mask designed in step S5, and a glass substrate covered with a perovskite metasurface structure layer and a transparent conductive layer is obtained. Step S7: Prepare a metal electrode structure on the perovskite metasurface structure layer of step S6 to obtain a glass substrate covered with a metal electrode structure, a perovskite metasurface structure layer and a transparent conductive layer.

5. The method for fabricating a perovskite-based all-Stokes polarization photodetector as described in claim 4, characterized in that, Step S1 specifically includes: placing the glass substrate into deionized water, acetone solution and anhydrous ethanol solution in sequence for ultrasonic cleaning for 5-10 minutes each; Step S2 specifically includes: drying the glass substrate after ultrasonic cleaning with nitrogen gas, and heating and drying it at 60-100℃ for 5-15 minutes.

6. The method for fabricating a perovskite-based all-Stokes polarization photodetector as described in claim 4, characterized in that, Step S3 specifically includes: placing the dried glass substrate into the vacuum chamber of the magnetron sputtering equipment and evacuating the vacuum to 5×10⁻⁶. -4 With a substrate vacuum level below Pa, argon gas is introduced as the working gas and the pressure is adjusted to 0.3-1.0 Pa. ITO target material is sputtered and deposited under sputtering power conditions of 50-150 W to form an ITO conductive film on the surface of the glass substrate. The thickness of the ITO conductive film is 100-200 nm.

7. The method for fabricating a perovskite-based all-Stokes polarization photodetector as described in claim 4, characterized in that, Step S4 specifically includes: placing a glass substrate with a transparent conductive layer in a spin coating device, dropping a perovskite precursor solution onto its surface and spin coating it to form a film, and dropping an anti-solvent chlorobenzene during the spin coating process to promote rapid nucleation of the film and form a uniform perovskite precursor solution film.

8. The method for fabricating a perovskite-based all-Stokes polarization photodetector as described in claim 4, characterized in that, Step S6 specifically includes: Step S601: Select a silicon wafer as the substrate, clean it with Piranha solution to remove organic contaminants, rinse it with deionized water and then dry it; Step S602: Spin-coat electron beam photoresist onto the dried silicon wafer surface. After pre-baking, use electron beam lithography to expose and develop the pattern of the photomask designed in step S5. Transfer the pattern to the silicon wafer through reactive ion etching to form a silicon master mold. Then, form an anti-adhesion layer on its surface by OTS vapor deposition. Step S603: Spin-coat UV-curable template adhesive onto the anti-adhesion layer on the surface of the silicon master mold, cover with PET film, cure by UV irradiation, and peel off to obtain a flexible nanoimprint mold with an inverse structure; Step S604: Cover the surface of the incompletely crystallized perovskite precursor solution film with the flexible nanoimprint mold, and imprint for 10 minutes at a temperature of 100°C and a pressure of 2.2MPa to allow the perovskite to complete structural replication and crystallization. Step S605: Slowly release the pressure, cool to room temperature, and then peel off the flexible nanoimprint mold to obtain a perovskite metasurface structure layer with micro-nano structure.

9. The method for fabricating a perovskite-based all-Stokes polarization photodetector as described in claim 4, characterized in that, Step S7 specifically includes: Step S701: Design a metal mask template, which has four symmetrically distributed electrode patterns. The positions of the four electrode patterns correspond to the electrode deposition areas around the perovskite metasurface structure layer. Step S702: Place the glass substrate covered with the perovskite metasurface structure layer and the transparent conductive layer on the sample stage of the thermal evaporation equipment, and tightly attach the metal mask above the surface of the perovskite metasurface structure layer or directly cover the surface of the perovskite metasurface structure layer, ensuring that the four patterns are aligned with the corresponding positions around the perimeter of the perovskite metasurface structure layer. Step S703: Evacuate the thermal evaporation equipment to a pressure below 5 × 10⁻⁶. -4 Pa is thermally deposited using chromium and gold as evaporation sources in sequence. The chromium layer has a thickness of 5-10 nm and serves as an adhesion layer. The gold layer has a thickness of 30-50 nm and serves as a conductive layer. Step S704: After the vapor deposition is completed, the glass substrate covered with the perovskite metasurface structure layer and the transparent conductive layer is removed from the thermal vapor deposition equipment, and the metal mask is peeled off. Four metal electrode units are symmetrically formed around the perovskite metasurface structure layer, and the four metal electrode units enclose the central photoresponse region. Step S705: The glass substrate with four symmetrically distributed metal electrode units obtained in step S704 is cleaned with nitrogen gas to obtain a fully Stokes polarized photodetector covered with a metal electrode structure.

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