Surface acoustic wave based linearly polarized light detector, preparation method and detection method thereof

Abstract

This invention discloses a surface acoustic wave (SAW)-based linearly polarized light detector, its fabrication method, and detection method, belonging to the field of optical detection technology. The SAW-based linearly polarized light detector includes: a piezoelectric substrate, on which a photosensitive layer, an input interdigital transducer, and an output interdigital transducer are disposed; the input and output interdigital transducers are symmetrically arranged on both sides of the photosensitive layer; wherein, the photosensitive layer is a composite heterojunction structure, the composite heterojunction structure comprising, from bottom to top, a metal thin film layer, a flexible elastomer layer, a two-dimensional anisotropic semiconductor layer, and a metal particle layer stacked sequentially. This invention effectively enhances the linear polarization sensitivity of the two-dimensional anisotropic semiconductor material and improves the dichroism ratio of the photocurrent without significantly increasing device complexity or fabrication difficulty, achieving passive wireless polarization detection of visible and near-infrared light.

Description

Technical Field

[0001] This invention belongs to the field of optical detection technology, specifically relating to a linearly polarized optical detector based on surface acoustic waves, its preparation method, and detection method. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Linear polarization detection has significant applications in infrared imaging, optical communication, remote sensing, and biomedical diagnostics. Traditional linear polarization detection primarily involves incorporating complex optical systems into the detection system, such as time-division multiplexing, aperture-division multiplexing, and amplitude-division multiplexing techniques to extract polarization information. However, these techniques suffer from low responsivity, slow response time, and low spatial resolution. With the development of integrated optics, integrated polarization detectors have emerged, mainly by designing metal nanogrids or filter structures on the detector to achieve selective absorption of light polarized in different directions. However, the introduction of these optical media undoubtedly increases the size and complexity of the device, hindering its integration into future micro-nano optoelectronic systems.

[0004] In recent years, using intrinsically anisotropic two-dimensional semiconductor materials as active layers for polarization detection has become a research hotspot. For example, two-dimensional van der Waals materials exhibit superior sensitivity to linearly polarized light due to their low dimensionality and low in-plane symmetry structure. Theoretically, most anisotropic two-dimensional materials can be used for linearly polarized light detectors. The core indicator for measuring the polarization sensitivity of a device is the photocurrent dichroic ratio (PDR), which is the ratio of the maximum to the minimum photocurrent under incident linearly polarized light in different directions.

[0005] Currently, the main methods for improving polarization sensitivity (PDR) fall into three categories: first, fabricating subwavelength artificial metamaterial micro / nanostructures on the surface of two-dimensional materials; second, through special device structure design, such as crystal stacking orientation control and PN heterostructure construction; and third, through external electric field control, such as ferroelectric polarization fields and strain fields. However, most heterojunctions struggle to achieve high-performance polarization detection solely based on the material's inherent properties, while introducing external control methods often increases device complexity and affects integration density. How to improve the polarization sensitivity of detectors without significantly impacting device complexity and integration density has become a pressing technical bottleneck.

[0006] Surface acoustic wave (SAW) technology has been explored for use in photodetectors. For example, a prior art discloses a SAW-assisted two-dimensional material photodetector, comprising a piezoelectric substrate, interdigitated electrodes disposed on the substrate, a two-dimensional semiconductor material located between the interdigitated electrodes, and source and drain electrodes disposed on the two-dimensional material. This approach utilizes SAW to modulate the band structure of the two-dimensional material, suppressing dark current and thus improving photodetection performance. However, this approach still requires the fabrication of additional source / drain electrodes on the two-dimensional material, and its modulation mechanism is relatively simple, failing to fully utilize the multiple modulation potential of SAW, and further neglecting to address enhanced detection of linearly polarized light. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a linearly polarized light detector based on surface acoustic waves, its preparation method and detection method. Without significantly increasing the complexity of the device and the difficulty of preparation, it effectively enhances the linear polarization sensitivity of two-dimensional anisotropic semiconductor materials, improves the dichroism ratio of photocurrent, and realizes passive wireless polarization detection of visible and near-infrared light.

[0008] Developing a linearly polarized light detector that is compact, highly integrated, highly polarization sensitive, and requires no additional electrodes is of significant practical importance and application value.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] In a first aspect, the technical solution of the present invention provides a linearly polarized optical detector based on surface acoustic waves, comprising: a piezoelectric substrate, on which a photosensitive layer, an input interdigital transducer, and an output interdigital transducer are disposed; the input interdigital transducer and the output interdigital transducer are symmetrically disposed on both sides of the photosensitive layer;

[0011] The photosensitive layer is a composite heterojunction structure, which includes a metal thin film layer, a flexible elastomer layer, a two-dimensional anisotropic semiconductor layer and a metal particle layer stacked sequentially from bottom to top.

[0012] In at least one embodiment, the thickness of the metal thin film layer is between 5 nm and 50 nm.

[0013] In at least one embodiment, the thickness of the flexible elastomer layer is between 2 nm and 10 nm, and its surface roughness does not exceed 0.5 nm.

[0014] In at least one embodiment, the two-dimensional anisotropic semiconductor layer is a single layer or multiple layers.

[0015] In at least one embodiment, the diameter of the metal nanoparticles in the metal particle layer is less than 100 nm.

[0016] In at least one embodiment, the piezoelectric substrate is made of a piezoelectric material;

[0017] And / or, both the input interdigital transducer and the output interdigital transducer include a pair of bus electrodes and multiple pairs of interdigital electrodes, with the multiple pairs of interdigital electrodes located between and connected to the pair of bus electrodes; the interdigital electrodes are made of a metal-like material or a metallic material.

[0018] Secondly, the technical solution of the present invention also provides a method for fabricating a linearly polarized optical detector based on surface acoustic waves, comprising:

[0019] Preparation of piezoelectric substrates;

[0020] An input interdigital transducer and an output interdigital transducer are fabricated on a piezoelectric substrate;

[0021] A photosensitive layer is fabricated on a piezoelectric substrate between the input interdigital transducer and the output interdigital transducer;

[0022] The photosensitive layer employs a composite heterojunction structure, and the fabrication steps of the composite heterojunction structure include:

[0023] A thin metal film layer is formed on a piezoelectric substrate;

[0024] A flexible elastomer layer is superimposed on a metal thin film layer;

[0025] A two-dimensional anisotropic semiconductor layer is superimposed on a flexible elastomer layer;

[0026] A layer of metal particles is stacked on a two-dimensional anisotropic semiconductor layer.

[0027] In at least one embodiment, it includes:

[0028] The metal thin film layer is connected to the piezoelectric substrate via transfer or growth deposition.

[0029] And / or, the flexible elastomer layer is prepared on the metal thin film layer by spin coating;

[0030] And / or, a two-dimensional anisotropic semiconductor layer is prepared on a flexible elastomer layer by mechanical exfoliation or growth deposition;

[0031] And / or, metal nanoparticles are dispersed onto a two-dimensional anisotropic semiconductor layer by spin coating or drop coating to form a metal particle layer.

[0032] Thirdly, the technical solution of the present invention also provides a method for detecting linearly polarized light based on surface acoustic waves, employing a linearly polarized light detector based on surface acoustic waves as described in the first aspect, and including the following steps:

[0033] An alternating current signal is applied to the input interdigital transducer to excite and generate surface acoustic waves.

[0034] Linearly polarized light is incident on the photosensitive layer, and the two-dimensional anisotropic semiconductor layer in the photosensitive layer absorbs the light energy to generate photogenerated carriers. The photogenerated carriers then undergo acoustic-electric coupling with the propagating surface acoustic wave.

[0035] The surface acoustic wave signal after passing through the photosensitive layer is received by the output interdigital transducer, and its frequency is measured.

[0036] The light response intensity of linearly polarized light is determined by the frequency variation of the surface acoustic wave signal output from the interdigital transducer.

[0037] In at least one embodiment, the following steps are also included:

[0038] Change the direction of the linearly polarized light incident on the photosensitive layer;

[0039] The maximum and minimum frequency shifts of the surface acoustic wave signals output by the interdigital transducer were measured under linearly polarized light incident from different directions.

[0040] The ratio of the maximum frequency shift to the minimum frequency shift is calculated and used as the polarization dichroism ratio to characterize the polarization sensitivity of the detector.

[0041] The beneficial effects of the above-described technical solution of the present invention are as follows:

[0042] 1) The linearly polarized light detector based on surface acoustic waves of this invention employs a photosensitive layer with a composite heterojunction structure. Driven by surface acoustic waves, it achieves multiple optical field enhancements: a two-dimensional anisotropic semiconductor layer enhances photoelectric anisotropy and forms a dynamic optical grating under the action of a periodic strain field; a metal thin film layer forms a dynamic optical grating to excite plasmons; and an elastic flexible body layer precisely transmits vibrations, enabling the metal nanoparticle layer and the metal thin film layer to form a dynamic plasmonic composite grating, achieving secondary optical field enhancement. The synergistic effect of multiple mechanisms significantly improves the detector's sensitivity to linearly polarized light and its absorption efficiency.

[0043] 2) The photosensitive layer of the present invention introduces an elastic flexible body layer between the metal thin film layer and the two-dimensional anisotropic semiconductor layer, which can accurately and efficiently transmit the nanoscale vibration of surface acoustic waves to the upper metal particle layer, so that a dynamically controllable plasma composite grating is formed between the metal nanoparticles and the metal thin film, thereby realizing the accurate transmission of vibration.

[0044] 3) The linearly polarized light detector based on surface acoustic waves of the present invention uses the frequency change of the surface acoustic waves themselves to characterize the light response, and defines the polarization dichroism ratio by the ratio of the maximum frequency shift to the minimum frequency shift under linearly polarized light in different directions. It does not require the fabrication of metal electrodes on two-dimensional anisotropic semiconductors, which not only simplifies the device structure and improves the integration, but also achieves higher detection sensitivity by utilizing the high sensitivity response mechanism of surface acoustic wave devices to acoustic-electric interaction.

[0045] 4) The period of the dynamic optical grating and plasma composite grating formed by the linear polarization detector based on surface acoustic waves of the present invention can be adjusted in real time by changing the electrical excitation frequency of the input interdigital transducer, so that the detector can adapt to incident light of different wavelengths, with strong dynamic controllability, greater flexibility and adaptability, and can be applied to a variety of application scenarios.

[0046] 5) The linearly polarized light detector based on surface acoustic waves of the present invention does not require the fabrication of electrodes on the photosensitive layer. It can directly feed back the light response by outputting the signal of the interdigital transducer, and has the potential for passive wireless detection, which can meet the detection needs in complex and harsh environments. Attached Figure Description

[0047] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0048] Figure 1 This is a schematic diagram of the linearly polarized light detector structure based on surface acoustic waves disclosed in Embodiment 1 of the present invention;

[0049] Figure 2 This is a schematic diagram of the side structure of the linearly polarized light detector based on surface acoustic waves disclosed in Embodiment 1 of the present invention.

[0050] In the figure: 1. Input interdigital transducer; 2. Output interdigital transducer; 3. Surface acoustic wave; 4. Piezoelectric substrate; 5. Photosensitive layer; 6. Metal thin film layer; 7. Flexible elastomer layer; 8. Two-dimensional anisotropic semiconductor layer; 9. Metal particle layer. Detailed Implementation

[0051] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0052] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0053] In this invention, terms such as "upper," "lower," "left," "right," "front," "back," "vertical," "horizontal," "side," and "bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only to facilitate the description of the structural relationships of the various components or elements of this invention and do not specifically refer to any component or element in this invention. They should not be construed as limiting the invention.

[0054] In this invention, terms such as "fixed connection," "connected," and "linked" should be interpreted broadly, indicating a fixed connection, an integral connection, or a detachable connection; a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can determine the specific meaning of these terms in this invention based on the specific circumstances, and they should not be construed as limitations on the invention.

[0055] Example 1

[0056] To address the challenge that most current linearly polarized optical detectors struggle to achieve high-performance polarization detection using only the inherent properties of their materials, a typical embodiment of this invention discloses a linearly polarized optical detector based on surface acoustic waves (SAWs). This detector employs a delayed-line SAW structure, selecting a suitable piezoelectric substrate 4. An input interdigital transducer 1 and an output interdigital transducer 2 are designed and fabricated on the substrate 4. Then, a composite heterojunction structure, consisting of a metal thin film layer 6, a flexible elastomer layer 7, a two-dimensional anisotropic semiconductor layer 8, and a metal particle layer 9, is fabricated on the delay line between the two interdigital transducers, serving as the photosensitive layer 5. By utilizing the periodic strain field and piezoelectric field generated by the SAWs, the photoelectric anisotropy of this composite heterojunction structure is modulated, exciting metal plasmons and enhancing light absorption, thus achieving a high-performance linearly polarized optical detector. The main advantages of this surface acoustic wave (SAW)-based linear polarization detector are: First, the strain field and local electric field generated by SAW are both micro- and nano-scale and tunable, which can significantly enhance the photoelectric anisotropy of anisotropic two-dimensional semiconductors; Second, the two-dimensional anisotropic semiconductor undergoes periodic deformation under the action of SAW, forming an optical grating, which can enhance polarization absorption anisotropy; Third, photogenerated carriers achieve spatial separation under the action of strain and piezoelectric fields, suppressing recombination; Fourth, the metal thin film excites plasmons under the action of periodic strain field, and enhances light absorption through photo-plasmon interaction; Fifth, SAW induces metal particles and metal films to form a dynamic plasma recombination grating, realizing secondary optical field enhancement; Sixth, the device converts photoelectric signals into acoustic-electric signals, and utilizes the high sensitivity response characteristics of SAW to acoustic-electric signals to achieve linear polarization sensitive detection, enabling passive wireless detection and meeting the needs of complex and harsh environments.

[0057] like Figure 1 and Figure 2 As shown, this embodiment discloses a linearly polarized light detector based on surface acoustic waves 3, including a piezoelectric substrate 4, on which a photosensitive layer 5, an input interdigital transducer 1, and an output interdigital transducer 2 are disposed. The input interdigital transducer 1 and the output interdigital transducer 2 are symmetrically disposed on both sides of the photosensitive layer 5.

[0058] The input interdigital transducer 1 generates surface acoustic waves 3 based on an alternating current signal, and the output interdigital transducer 2 receives the surface acoustic wave 3 signal after passing through the photosensitive layer 5 and converts it into an electrical signal for output. Both the input interdigital transducer 1 and the output interdigital transducer 2 include a pair of bus electrodes and multiple pairs of interdigital electrodes. The multiple pairs of interdigital electrodes are located between and connected to the pair of bus electrodes. Specifically, a pair of bus electrodes includes a first bus electrode and a second bus electrode that are parallel to each other; each pair of interdigital electrodes includes a first finger and a second finger. Multiple first fingers are provided on one side of the first bus electrode, and multiple second fingers that cooperate with the first fingers are provided on the side of the second bus electrode close to the first bus electrode; the multiple second fingers and the multiple first fingers intersect each other to form an interdigital transducer.

[0059] As a further embodiment, the input interdigital transducer 1 and the output interdigital transducer 2 are made of a metal-like material or a metallic material, wherein the metallic material is one or more of gold, silver, indium, copper or titanium, etc.; and the metal-like material is graphene, etc.

[0060] The surface of the piezoelectric substrate 4 can generate a periodic strain field and a piezoelectric field using surface acoustic waves 3. Its material is a piezoelectric material, such as lithium niobate. ), quartz, gallium nitride (GaN), aluminum nitride (AlN), barium titanate ( Piezoelectric materials such as lead zirconate titanate (PZT) or lead zirconate titanate piezoelectric ceramics.

[0061] The photosensitive layer 5 is located on the delay line between the input interdigital transducer 1 and the output interdigital transducer 2. It is a composite heterojunction structure, which includes a metal thin film layer 6, a flexible elastomer layer 7, a two-dimensional anisotropic semiconductor layer 8 and a metal particle layer 9 stacked sequentially from bottom to top. That is, the metal thin film layer 6 is stacked on the piezoelectric substrate 4, the flexible elastomer layer 7 is stacked on the metal thin film layer 6, the two-dimensional anisotropic semiconductor layer 8 is stacked on the flexible elastomer layer 7, and the metal particle layer 9 is stacked on the two-dimensional anisotropic semiconductor layer 8.

[0062] The metal thin film layer 6 is connected to the piezoelectric substrate 4 via transfer or growth deposition. To facilitate deformation under the strain field generated by the surface acoustic wave 3, the thickness of the metal thin film layer 6 can be set between 5 nm and 50 nm, depending on the material properties. As a further embodiment, the material of the metal thin film layer 6 is silver, gold, or aluminum, etc.

[0063] The flexible elastomer layer 7 is prepared on the metal thin film layer 6 by a suitable method such as spin coating. To facilitate the transfer of deformation from the metal thin film layer 6 to the two-dimensional anisotropic semiconductor layer 8, the thickness of the flexible elastomer layer 7 is set between 2 nm and 10 nm, and its surface roughness does not exceed 0.5 nm. As a further embodiment, the material of the flexible elastomer layer 7 is polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), or polyethylene naphthalate (PEN), etc.

[0064] The two-dimensional anisotropic semiconductor layer 8 is prepared on the flexible elastomer layer 7 by mechanical exfoliation or growth deposition, and its material can be rhenium disulfide (rhenium). rhenium diselenide ( Zirconium trisulfide ( Or germanium arsenide (GeAs), etc. As a further embodiment, the two-dimensional anisotropic semiconductor layer 8 is a single layer or multiple layers.

[0065] Metal nanoparticles in the metal particle layer 9 are dispersed onto the two-dimensional anisotropic semiconductor layer 8 by spin coating or drop coating to form the metal particle layer 9. To generate visible-near-infrared plasmons, the diameter of the metal nanoparticles is less than 100 nm to cover the visible-near-infrared band. As a further embodiment, the material of the metal nanoparticles is gold nanoparticles or silver nanoparticles, etc.

[0066] This embodiment discloses a linearly polarized light detector based on surface acoustic waves 3, the specific working principle of which is as follows:

[0067] When an alternating current signal of a specific frequency is applied to the input interdigital transducer 1, surface acoustic waves 3 are excited by the inverse piezoelectric effect. The surface acoustic waves 3 propagate along the surface of the piezoelectric substrate 4 towards the output interdigital transducer 2 in an armchair or zigzag crystal orientation. The applied frequency is matched with the period of the interdigital electrodes.

[0068] When the surface acoustic wave 3 propagates to the region of the photosensitive layer 5, which employs a composite heterojunction structure, a periodic strain field and a piezoelectric field are generated. This periodic strain field acts on the two-dimensional anisotropic semiconductor layer 8, enhancing its photoelectric anisotropy and causing it to form a dynamic optical grating, thus suppressing photogenerated carrier recombination; it also acts on the metal thin film layer 6, causing it to form a dynamic optical grating and exciting plasmons, thereby enhancing light absorption through photo-plasmon interactions; simultaneously, the elastic flexible body layer precisely transmits the nanoscale vibration of the surface acoustic wave 3 to the upper metal particle layer 9, causing the metal nanoparticles to approach or move away from the two-dimensional anisotropic semiconductor layer 8. The surface acoustic wave 3 induces the metal nanoparticles and the metal thin film layer 6 to form a dynamic plasma composite grating, achieving secondary optical field enhancement.

[0069] When linearly polarized light is incident on the photosensitive layer 5, which employs a composite heterojunction structure, the absorption of linearly polarized light in a specific direction is significantly enhanced under the synergistic effect of the aforementioned multiple light field enhancement mechanisms. This generates a large number of photogenerated carriers, which then undergo acoustic-electric coupling with the propagating surface acoustic wave 3, causing a change in the propagation characteristics (mainly frequency) of the surface acoustic wave 3.

[0070] The output interdigital transducer 2 receives the surface acoustic wave 3 signal after passing through the photosensitive layer 5 with a composite heterojunction structure, and converts it into an electrical signal output. By measuring the offset of the frequency of the output electrical signal relative to the reference frequency when there is no light, the light response intensity can be characterized, thus realizing high-performance linear polarization light detection of visible and near-infrared light.

[0071] This embodiment discloses a linear polarization detector based on surface acoustic wave 3 (SAW3). It eliminates the need to fabricate metal electrodes on a two-dimensional anisotropic semiconductor. The device's optical response is characterized by testing the frequency change of SAW3 under illumination using an interdigital transducer, thereby achieving passive wireless polarization detection of visible and near-infrared light.

[0072] Example 2

[0073] In a typical embodiment of the present invention, this embodiment discloses a method for fabricating a linearly polarized optical detector based on surface acoustic waves 3, specifically including the following steps:

[0074] S1. Prepare piezoelectric substrate 4;

[0075] S2. An input interdigital transducer 1 and an output interdigital transducer 2 are fabricated on a piezoelectric substrate 4;

[0076] S3. A photosensitive layer 5 is prepared on a piezoelectric substrate 4 between the input interdigital transducer 1 and the output interdigital transducer 2.

[0077] In step S1, the piezoelectric substrate 4 is made of a piezoelectric material, such as lithium niobate (… ), quartz, gallium nitride (GaN), aluminum nitride (AlN), barium titanate ( It is one or more of the following piezoelectric materials: lead zirconate titanate (PZT) or lead zirconate titanate (PZT).

[0078] In step S2, both the input interdigital transducer 1 and the output interdigital transducer 2 include a pair of bus electrodes and multiple pairs of interdigital electrodes. The multiple pairs of interdigital electrodes are located between the pair of bus electrodes and connected to the bus electrodes. Specifically, the pair of bus electrodes includes a first bus electrode and a second bus electrode that are parallel to each other; each pair of interdigital electrodes includes a first finger and a second finger. Multiple first fingers are provided on one side of the first bus electrode, and multiple second fingers that cooperate with the first fingers are provided on the side of the second bus electrode close to the first bus electrode; the multiple second fingers and the multiple first fingers intersect each other to form an interdigital transducer.

[0079] As a further embodiment, the input interdigital transducer 1 and the output interdigital transducer 2 are made of a metal-like material or a metallic material, wherein the metallic material is one or more of gold, silver, indium, copper or titanium, etc.; and the metal-like material is graphene, etc.

[0080] In step S3, a photosensitive layer 5 is fabricated on the piezoelectric substrate 4 on the delay line between the input interdigital transducer 1 and the output interdigital transducer 2. This photosensitive layer 5 employs a composite heterojunction structure, and the specific fabrication steps include:

[0081] S31. A metal thin film layer 6 is formed on the piezoelectric substrate 4.

[0082] In this step, the metal thin film layer 6 is connected to the piezoelectric substrate 4 by transfer or growth deposition. To facilitate deformation under the strain field generated by the surface acoustic wave 3, the thickness of the metal thin film layer 6 can be set between 5 nm and 50 nm according to the material properties.

[0083] As a further embodiment, the material of the metal thin film layer 6 is silver, gold, or aluminum, etc.

[0084] S32. A flexible elastomer layer 7 is superimposed on the metal thin film layer 6.

[0085] In this step, the flexible elastomer layer 7 is prepared on the metal thin film layer 6 by a suitable method such as spin coating. In order to facilitate the deformation of the metal thin film layer 6 to be conducted to the two-dimensional anisotropic semiconductor layer 8, the thickness of the flexible elastomer layer 7 is set between 2 nm and 10 nm, and its surface roughness does not exceed 0.5 nm.

[0086] As a further embodiment, the material of the flexible elastomer layer 7 is polydimethylsiloxane (PDMS), polyethylene terephthalate (PET), or polyethylene naphthalate (PEN), etc.

[0087] S33. A two-dimensional anisotropic semiconductor layer 8 is superimposed on the flexible elastomer layer 7.

[0088] In this step, the two-dimensional anisotropic semiconductor layer 8 is prepared on the flexible elastomer layer 7 by mechanical exfoliation or growth deposition, and its material can be rhenium disulfide (rhenium disulfide). rhenium diselenide ( Zirconium trisulfide ( (e.g., germanium arsenide (GeAs)).

[0089] As a further implementation, the two-dimensional anisotropic semiconductor layer 8 is a single layer or multiple layers.

[0090] S34. A metal particle layer 9 is superimposed on the two-dimensional anisotropic semiconductor layer 8.

[0091] In this step, metal nanoparticles are dispersed onto a two-dimensional anisotropic semiconductor layer 8 by spin coating or drop coating to form a metal particle layer 9. In order to generate visible-near-infrared plasmons, the diameter of the metal nanoparticles is less than 100 nm to cover the visible-near-infrared band.

[0092] As a further embodiment, the material of the metal nanoparticles is gold nanoparticles or silver nanoparticles, etc.

[0093] Example 3

[0094] In a typical embodiment of the present invention, this embodiment provides a method for detecting linearly polarized light based on surface acoustic waves 3, employing a linearly polarized light detector based on surface acoustic waves 3 as described in Embodiment 1, specifically including the following steps:

[0095] S1. Apply an alternating current signal to the input interdigital transducer 1 to generate surface acoustic waves 3.

[0096] In this step, an alternating current signal of a specific frequency is applied to the input interdigital transducer 1. Due to the inverse piezoelectric effect, the input interdigital transducer 1 excites surface acoustic waves 3. The surface acoustic waves 3 propagate along the surface of the piezoelectric substrate 4 towards the output interdigital transducer 2 in an armchair or zigzag crystal orientation. The applied frequency is matched with the interdigital electrode period.

[0097] S2. Linearly polarized light is incident on the photosensitive layer 5. The two-dimensional anisotropic semiconductor layer 8 in the photosensitive layer 5 absorbs the light energy to generate photogenerated carriers. The photogenerated carriers interact with the propagating surface acoustic wave 3 via acoustic-electric coupling.

[0098] In this step, when the surface acoustic wave 3 propagates to the region where the photosensitive layer 5 with the composite heterojunction structure is located, a periodic strain field and a piezoelectric field are generated. This periodic strain field acts on the two-dimensional anisotropic semiconductor layer 8, enhancing its photoelectric anisotropy and forming a dynamic optical grating, suppressing photogenerated carrier recombination; it acts on the metal thin film layer 6, forming a dynamic optical grating and exciting plasmons, enhancing light absorption through photo-plasmon interaction; simultaneously, the elastic flexible body layer precisely transmits the nanoscale vibration of the surface acoustic wave 3 to the upper metal particle layer 9, causing the metal nanoparticles to approach or move away from the two-dimensional anisotropic semiconductor layer 8. The surface acoustic wave 3 induces the metal nanoparticles and the metal thin film layer 6 to form a dynamic plasmon composite grating, achieving secondary light field enhancement.

[0099] When linearly polarized light is incident on the photosensitive layer 5, which employs a composite heterojunction structure, the absorption of linearly polarized light in a specific direction is significantly enhanced under the synergistic effect of the aforementioned multiple light field enhancement mechanisms. This generates a large number of photogenerated carriers, which then undergo acoustic-electric coupling with the propagating surface acoustic wave 3, causing a change in the propagation characteristics (mainly frequency) of the surface acoustic wave 3.

[0100] S3. Receive the surface acoustic wave 3 signal after passing through the photosensitive layer 5 through the output interdigital transducer 2, and measure its frequency.

[0101] In this step, the output interdigital transducer 2 receives the surface acoustic wave 3 signal after passing through the photosensitive layer 5 with a composite heterojunction structure, converts it into an electrical signal output, and measures the frequency of the output signal.

[0102] S4. Determine the light response intensity of linearly polarized light based on the frequency change of the surface acoustic wave 3 signal output by the interdigital transducer 2.

[0103] In this step, the frequency change of the surface acoustic wave 3 signal output by the interdigital transducer 2 is determined by calculating the offset of the frequency of the output signal relative to the reference frequency when there is no light. This is used to characterize the light response intensity, determine the light response intensity of linearly polarized light, and realize high-performance linearly polarized light detection for visible and near-infrared light.

[0104] As a further implementation method, the following steps are also included:

[0105] S5. Change the direction of the linearly polarized light incident on the photosensitive layer 5;

[0106] S6. Measure the maximum frequency shift of the surface acoustic wave 3 signal output by the interdigital transducer 2 under linearly polarized light incident from different directions. and minimum frequency shift ;

[0107] S7. Calculate the ratio of the maximum frequency shift to the minimum frequency shift, specifically expressed as:

[0108]

[0109] In the formula, It represents the polarization dichroism ratio, which can characterize the polarization sensitivity of the detector.

[0110] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A linearly polarized light detector based on surface acoustic waves, characterized in that, include: A piezoelectric substrate, on which a photosensitive layer, an input interdigital transducer, and an output interdigital transducer are disposed; the input interdigital transducer and the output interdigital transducer are symmetrically disposed on both sides of the photosensitive layer. The photosensitive layer is a composite heterojunction structure, which includes a metal thin film layer, a flexible elastomer layer, a two-dimensional anisotropic semiconductor layer and a metal particle layer stacked sequentially from bottom to top.

2. The linearly polarized light detector based on surface acoustic waves as described in claim 1, characterized in that, The thickness of the metal thin film layer is between 5 nm and 50 nm.

3. The linearly polarized light detector based on surface acoustic waves as described in claim 1, characterized in that, The thickness of the flexible elastomer layer is between 2nm and 10nm, and its surface roughness does not exceed 0.5nm.

4. The linearly polarized light detector based on surface acoustic waves as described in claim 1, characterized in that, Two-dimensional anisotropic semiconductor layers can be single-layered or multi-layered.

5. The linearly polarized light detector based on surface acoustic waves as described in claim 1, characterized in that, The diameter of the metal nanoparticles in the metal particle layer is less than 100 nm.

6. The linearly polarized light detector based on surface acoustic waves as described in claim 1, characterized in that, The piezoelectric substrate is made of piezoelectric material; And / or, both the input interdigital transducer and the output interdigital transducer include a pair of bus electrodes and multiple pairs of interdigital electrodes, with the multiple pairs of interdigital electrodes located between and connected to the pair of bus electrodes; the interdigital electrodes are made of a metal-like material or a metallic material.

7. A method for fabricating a linearly polarized optical detector based on surface acoustic waves, characterized in that, include: Preparation of piezoelectric substrates; An input interdigital transducer and an output interdigital transducer are fabricated on a piezoelectric substrate; A photosensitive layer is fabricated on a piezoelectric substrate between the input interdigital transducer and the output interdigital transducer; The photosensitive layer employs a composite heterojunction structure, and the fabrication steps of the composite heterojunction structure include: A thin metal film layer is formed on a piezoelectric substrate; A flexible elastomer layer is superimposed on a metal thin film layer; A two-dimensional anisotropic semiconductor layer is superimposed on a flexible elastomer layer; A layer of metal particles is stacked on a two-dimensional anisotropic semiconductor layer.

8. The method for fabricating a linearly polarized optical detector based on surface acoustic waves as described in claim 7, characterized in that, include: The metal thin film layer is connected to the piezoelectric substrate via transfer or growth deposition. And / or, the flexible elastomer layer is prepared on the metal thin film layer by spin coating; And / or, a two-dimensional anisotropic semiconductor layer is prepared on a flexible elastomer layer by mechanical exfoliation or growth deposition; And / or, metal nanoparticles are dispersed onto a two-dimensional anisotropic semiconductor layer by spin coating or drop coating to form a metal particle layer.

9. A linearly polarized light detection method based on surface acoustic waves, characterized in that, The linearly polarized light detector based on surface acoustic waves as described in any one of claims 1-6 includes the following steps: An alternating current signal is applied to the input interdigital transducer to excite and generate surface acoustic waves. Linearly polarized light is incident on the photosensitive layer, and the two-dimensional anisotropic semiconductor layer in the photosensitive layer absorbs the light energy to generate photogenerated carriers. The photogenerated carriers then undergo acoustic-electric coupling with the propagating surface acoustic wave. The surface acoustic wave signal after passing through the photosensitive layer is received by the output interdigital transducer, and its frequency is measured. The light response intensity of linearly polarized light is determined by the frequency variation of the surface acoustic wave signal output from the interdigital transducer.

10. The linearly polarized light detection method based on surface acoustic waves as described in claim 9, characterized in that, It also includes the following steps: Change the direction of the linearly polarized light incident on the photosensitive layer; The maximum and minimum frequency shifts of the surface acoustic wave signals output by the interdigital transducer were measured under linearly polarized light incident from different directions. The ratio of the maximum frequency shift to the minimum frequency shift is calculated and used as the polarization dichroism ratio to characterize the polarization sensitivity of the detector.

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