Focal plane polarized photoelectric detector with bifocal liquid crystal lens integrated on surface and preparation method and application thereof

Abstract

The invention discloses a focal plane polarized photoelectric detector with a bifocal liquid crystal lens integrated on the surface and a preparation method and application of the focal plane polarized photoelectric detector, and relates to the technical field of detectors. The device comprises a liquid crystal bifocal lens used for separating incident circularly polarized light CPL into left-handed circularly polarized light LCP and right-handed circularly polarized light RCP, and focusing the left-handed circularly polarized light LCP and the right-handed circularly polarized light RCP to different spatial positions; and the distance between two detection channels of the two-dimensional MoTe2 dual-channel photoelectric detector is matched with the focus offset of the liquid crystal bifocal lens, and the two detection channels are respectively used for receiving optical signals of the LCP and the RCP and carrying out independent detection. The bifocal liquid crystal lens and the two-dimensional MoTe2 photoelectric detector are integrated, ultra-sensitive and high-resolution circularly polarized light detection is achieved, the problems that a traditional circularly polarized detector is large in size, low in sensitivity and complex in installation and adjustment are solved, and a high-performance and low-cost new-generation photoelectric detection scheme is provided for the fields of quantum optics, biomedical detection and the like.

Description

Technical Field

[0001] This invention relates to the field of detector technology, specifically to a focal plane polarization photodetector with a surface-integrated dual-focus liquid crystal lens, its fabrication method, and its application. Background Technology

[0002] Division-of-focal-plane (DoFP) polarization detection integrates micro-polarization optical elements onto the surface of a focal plane detector, enabling simultaneous detection of different polarization components. With advancements in micro / nano fabrication processes, the ability to fabricate and integrate tiny optical elements has become possible. DoFP polarization detection technology can obtain the polarization information of the object under test through a single exposure of a static or dynamic scene, achieving real-time dynamic polarization detection and demonstrating unique advantages in miniaturization and integration. Although DoFP polarization detection technology has made significant progress, it still faces several challenges: First, achieving perfect alignment between the micro-polarization array and the detector's focal plane is difficult, and the gap between them leads to crosstalk between adjacent pixels, increasing detection uncertainty. As pixel size decreases, the extinction ratio of the micro-polarization array decreases, making crosstalk even more difficult to resolve. Furthermore, the reduction in pixel size leads to a decrease in the area ratio of the photosensitive region, thereby reducing the device's light utilization and lowering performance parameters such as photoresponsivity, detectivity, and external quantum efficiency. While microlenses can effectively address crosstalk and light utilization issues, they also increase structural complexity and size, hindering the miniaturization trend of devices. Secondly, achieving full Stocks polarization detection requires integrating multiple polarization filters, including circular and multi-angle linear polarization filters, onto the micro-polarization array. This increases the difficulty and complexity of device design and fabrication, making true full Stocks polarization detection difficult. Finally, infrared polarization photodetectors based on traditional thin-film narrow-bandgap semiconductors (such as Si, GaN, InGaAs, InSb, and HgCdTe) typically exhibit large dark currents and excessively high signal-to-noise ratios at room temperature, resulting in image quality that fails to meet everyday requirements. Only after cryogenic cooling can shorter response times, higher sensitivity, and higher signal-to-noise ratios be achieved. However, the presence of cooling devices not only increases manufacturing costs but also enlarges the system's size and weight, hindering portability.

[0003] Liquid crystals are a special state of matter between solids and liquids, exhibiting the fluidity of liquids and the anisotropy of solids. Therefore, they were named "liquid crystals" by the German physicist Lehmann. Most common liquid crystal molecules have a rod-shaped asymmetric structure, resulting in significant anisotropy in their physical properties such as dielectric constant, refractive index, and conductivity. At the molecule level, the physical properties exhibited parallel to and perpendicular to the direction of the liquid crystal molecule's direction of orientation differ. The fluidity of liquid crystal molecules makes their arrangement easily altered by external influences, further affecting their physical properties and making sensing using liquid crystal molecules possible. The anisotropy of liquid crystals manifests as birefringence in terms of refractive index. Similar to birefringence in crystals, when light propagates through a crystal, the incident light produces two linearly polarized rays with mutually perpendicular electric vectors. One type of light, called the ordinary ray (o-ray), does not change its propagation speed regardless of its direction of propagation. Its electric vector vibration direction is perpendicular to the optical axis of the liquid crystal, and the corresponding refractive index is denoted as the ordinary ray refractive index n. o The propagation speed of another type of light changes due to the change in the angle between the electric vector vibration direction and the optical axis of the liquid crystal caused by the change in the propagation direction. This light is called extraordinary light (e-ray). When the electric vector vibration direction of the extraordinary light is the same as the direction of the optical axis of the liquid crystal, its propagation speed is the minimum, and the corresponding refractive index is the maximum, denoted as the extraordinary light refractive index n of the liquid crystal. e Usually n e and n o The difference Δn is used to measure the birefringence performance of liquid crystal materials.

[0004] The basic model of optical phased arrays is derived from microwave phased arrays. Its basic architecture consists of a large number of independent phased array units, each capable of individually modulating the incident light phase, thus achieving wavefront modulation. After specific phase modulation, the outgoing wave diffracts in a designated direction, ultimately achieving directional propagation of the beam. The principle of liquid crystal optical phased arrays is similar, utilizing liquid crystal molecules as independent phased array units to achieve phase modulation. Different phase modulations are achieved by controlling the spatial director of the liquid crystal molecules. Liquid crystal polarization lenses (LCPLs), as typical micro-optical components, also possess the advantages of traditional dielectric superlenses, such as small size, thinness, and ease of integration. More importantly, compared to traditional dielectric superlenses, LCPLs also have advantages such as simple structure, low fabrication difficulty, low cost, and high focusing efficiency.

[0005] Therefore, we propose a focal plane polarization photodetector with surface-integrated dual-focus liquid crystal lens, its fabrication method, and its application, in order to solve the problems mentioned above.

[0006] The information disclosed above in this background section is only for enhancing the understanding of the background technology of this invention, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a focal plane polarization photodetector with a surface-integrated dual-focus liquid crystal lens, its fabrication method, and its application, to meet the requirements of high performance, miniaturization, and low power consumption for circular polarization detection.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens, comprising: A liquid crystal bifocal lens (LCBL) is used to separate incident circularly polarized light (CPL) into left-hand circularly polarized light (LCP) and right-hand circularly polarized light (RCP), and focus them to different spatial positions. The two-dimensional MoTe2 dual-channel photodetector has a spacing between its two detection channels that matches the focal offset of the liquid crystal bifocal lens, and is used to receive LCP and RCP optical signals and perform independent detection, respectively.

[0009] Preferably, the device further includes a Si substrate and a SiO2 dielectric layer formed on the surface of the Si substrate. An electrode group including electrode one, electrode two and electrode three is symmetrically arranged on the SiO2 dielectric layer. A MoTe2 thin film is provided between electrode one and electrode two, and a MoTe2 thin film of the same thickness is provided between electrode two and electrode three. A quartz substrate is provided above the electrodes and the MoTe2 thin film, and a dual-focus liquid crystal lens is provided on the quartz substrate.

[0010] Preferably, the bifocal liquid crystal lens is based on geometric phase (Pancharatnam-Berry phase) modulation, and its phase distribution satisfies the following formula: ; Where A and B are the relative amplitudes of LCP and RCP, respectively; U LCP and U RCP Let LCP and RCP be the focal light field distributions, respectively, and their expressions are: ; in, Let f be the wave vector, and (x1,y1,f1) and (x2,y2,f2) are the focal positions of LCP and RCP, respectively.

[0011] Preferably, the channel width of the MoTe2 dual-channel detector is matched with the focusing spot diameter of the liquid crystal bifocal lens to improve photon utilization; the center-to-center distance between the two detection channels is consistent with the lateral distance of the focal point of the liquid crystal bifocal lens; the thickness of the MoTe2 film is 30-35 nm (characterized by atomic force microscopy AFM), and the thickness difference between the two channels does not exceed 3 nm to ensure the consistency of photoelectric response.

[0012] Preferably, the performance indicators of the detector are: extinction ratio > 80:1 (intensity ratio of LCP to RCP); responsivity up to 120 A / W (wavelength 1064 nm, optical power 0.5 mW); detectivity up to 3.6 × 10¹² Jones; response time (rise / fall time) < 125 ms.

[0013] The present invention also provides a method for fabricating a focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens as described above, comprising the following steps: Step 1: Fabrication of a liquid crystal bifocal lens: Step 1.1: First, the quartz substrate is ultrasonically cleaned and dried. Then, it is placed in an ultraviolet ozone cleaner to further treat the organic matter on the surface of the quartz substrate. Step 1.2: Then spin-coat the SD1 solution onto the surface of the quartz substrate and dry it to evaporate the SD1 solution, thus obtaining the SD1 substrate; Step 1.3: The SD1 substrate is exposed using a DMD micro-exposure system, and a polarization distribution pattern is obtained through multi-step exposure. Step 1.4: Then, the liquid crystal monomers and photoinitiator are spin-coated onto the surface of the SD1 substrate. At this time, the liquid crystal monomers are aligned along the SD1 alignment direction to form the exposed pattern. Step 1.5: After polymerization under a UV curing lamp, the photoinitiator triggers cross-linking of the liquid crystal monomers to form a liquid crystal bifocal lens 1;

[0014] Step 2: Fabrication of a dual-channel MoTe2 photodetector: Step 2.1: First, the MoTe2 bulk single crystal is peeled off to a few layers (≤50nm) using special two-dimensional material tape and transferred to the surface of SiO2 / Si substrate; Step 2.2: Locate and mark two MoTe2 films of suitable position and size under a microscope; Step 2.3: Spin-coat and cure photoresist, construct electrode patterns using laser direct writing, and develop; Step 2.4: Prepare the electrode assembly using a magnetron sputtering apparatus; Step 2.5: Remove excess photoresist from the Si substrate surface to obtain a dual-channel MoTe2 photodetector; Step 3, Device Integration and Alignment: The liquid crystal dual-focal lens is integrated onto the surface of the dual-channel MoTe2 photodetector and aligned under a microscope to ensure that the LCP / RCP focal points of the liquid crystal dual-focal lens coincide with the centers of the two channels of MoTe2, forming a focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens.

[0015] Preferably, the DMD exposure system has a resolution of 1024×768 pixels and a single micromirror size of 13.68×13.68 μm, which enables high-precision liquid crystal alignment control.

[0016] Preferably, the electrode material of the dual-channel MoTe2 photodetector is Au (50 nm) / Ti (5 nm) to reduce contact resistance.

[0017] This invention also provides applications of the focal plane polarization photodetector with the surface-integrated dual-focal liquid crystal lens as described above, the applications including: Circular polarization state resolution applied in quantum optical communication; Polarization coding detection applied to optical information encryption systems; Detection of optical signals of chiral molecules in biosensing.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention innovatively proposes a focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens. By integrating the dual-focal liquid crystal lens (LCBL) with a two-dimensional MoTe2 photodetector, ultra-sensitive and high-resolution circular polarization light detection is achieved. This solves the problems of large size, low sensitivity, and complex assembly and adjustment of traditional circular polarization detectors, and provides a high-performance and low-cost next-generation photoelectric detection solution for fields such as quantum optics and biomedical detection.

[0019] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the preparation process of the present invention; Figure 2 This is a phase distribution diagram of the dual-focus liquid crystal lens of the present invention; Figure 3 This is a schematic diagram of the dual-channel MoTe2 photodetector structure of the present invention; Figure 4This is a schematic diagram of the focal plane polarization photoelectric detection structure of the surface-integrated dual-focus liquid crystal lens of the present invention; Figure 5 This is a schematic diagram of the timing curve of the dual-channel circuit of the present invention.

[0021] In the figure: 1. Liquid crystal bifocal lens; 2. Quartz substrate; 3. Electrode assembly; 4. MoTe2 thin film; 5. SiO2 dielectric layer; 6. Si substrate. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 A surface-integrated dual-focal liquid crystal lens-based focal plane polarization photodetector includes a liquid crystal dual-focal lens 1 and a two-dimensional MoTe2 dual-channel photodetector.

[0024] The liquid crystal dual-focal lens 1 is used to separate the incident circularly polarized light CPL into left-hand circularly polarized light LCP and right-hand circularly polarized light RCP, and focus the two to different spatial positions. The spacing between the two detection channels of the two-dimensional MoTe2 dual-channel photodetector is matched with the focal offset of the liquid crystal bifocal lens 1, and is used to receive LCP and RCP optical signals and perform independent detection, respectively.

[0025] Specifically, it also includes a Si substrate 6 and a SiO2 dielectric layer 5 formed on the surface of the Si substrate 6. An electrode group 3, including electrode one, electrode two and electrode three, is symmetrically arranged on the SiO2 dielectric layer 5. A MoTe2 thin film 4 is arranged between electrode one and electrode two. A MoTe2 thin film 4 of the same thickness is arranged between electrode two and electrode three. A quartz substrate 2 is arranged above the electrode group 3 and the MoTe2 thin film 4. A liquid crystal bifocal lens 1 is arranged on the quartz substrate.

[0026] Specifically, the liquid crystal bifocal lens 1 is based on geometric phase modulation, and its phase distribution satisfies the following formula: ; Where A and B are the relative amplitudes of LCP and RCP, respectively; U LCP and U RCP Let LCP and RCP be the focal light field distributions, respectively, and their expressions are: ; in, Let f be the wave vector, and (x1,y1,f1) and (x2,y2,f2) are the focal positions of LCP and RCP, respectively.

[0027] Specifically, the focal length of the liquid crystal bifocal lens 1 is 500 μm, and the lateral distance between the focal points of the LCP and RCP is 100 μm, i.e. , .

[0028] Specifically, the channel width of the MoTe2 dual-channel detector is 10 μm, which matches the focusing spot diameter of the liquid crystal bifocal lens 1 to improve photon utilization; the center-to-center distance between the two detection channels is 100 μm, which is consistent with the lateral distance of the focal point of the liquid crystal bifocal lens 1; the thickness of the MoTe2 thin film 4 is 30-35 nm, and the thickness difference between the two channels does not exceed 3 nm to ensure the consistency of photoelectric response.

[0029] Example 2

[0030] A method for fabricating a focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens for a wavelength of 1064 nm includes the following steps: Step 1: Fabrication of liquid crystal bifocal lens 1: Step 1.1: Determine the parameters of the liquid crystal bifocal lens 1: wavelength 1064 nm, focal length 500 μm, and focal lateral distance 100 μm. Based on the above parameters, calculate the phase distribution of the liquid crystal bifocal lens 1.

[0031] Step 1.2: Substrate Pretreatment Quartz substrate 2 with a thickness of 0.5 mm was selected and ultrasonically cleaned with acetone, ethanol and deionized water for 15 minutes in sequence. After drying, it was placed in an ultraviolet ozone cleaner for 20 minutes to remove organic matter from the surface. Step 1.3: Preparation of the photo-alignment layer A 0.5% concentration of SD1 photoaligning agent (dissolved in N,N-dimethylformamide) was spin-coated onto the surface of quartz substrate 2 (3000 rpm, 30 s), and then baked on a hot plate at 100 °C for 10 minutes to form a uniform SD1 alignment layer. Step 1.4: Patterned Exposure A digital micromirror device (DMD) exposure system with a resolution of 1024×768 and a single micromirror size of 13.68×13.68 μm is employed, enabling high-precision liquid crystal alignment control; a dual-focus phase pattern is generated under computer control, such as... Figure 2 As shown; Step 1.5: Spin-coat LCP015 liquid crystal monomer (15% toluene solution containing 1% photoinitiator Irgacure 819) onto the SD1 substrate (1500 rpm, 4 cycles) to orient the liquid crystal molecules along the SD1 pattern. Cure under UV light (365 nm, 20 mW / cm², 5 minutes) to form a liquid crystal bifocal lens 1 with a thickness of 2-3 μm.

[0032] Step 2: Fabrication of a dual-channel MoTe2 photodetector: Step 2.1: Determine the detector parameters. According to the design parameters of the bifocal liquid crystal lens, the channel spacing is 100μm.

[0033] Step 2.2: MoTe2 thin film transfer A few-layer MoTe2 thin film 4 was obtained from a bulk MoTe2 single crystal using a mechanical exfoliation method and transferred to the surface of a SiO2 / Si substrate 6.

[0034] Step 2.3: Electrode preparation Photoresist was spin-coated and cured; electrode patterns were constructed using laser direct writing and developed; electrode assembly 3 was fabricated using a magnetron sputtering apparatus; excess photoresist was removed from the surface of the Si substrate 6, finally yielding a dual-channel MoTe2 photodetector (as shown in the attached image). Figure 3 (As shown).

[0035] The electrode material of the dual-channel MoTe2 photodetector is Au (50 nm) / Ti (5 nm) to reduce contact resistance.

[0036] Step 3, Device Integration and Alignment: A liquid crystal dual-focal lens 1 is integrated onto the surface of a dual-channel MoTe2 photodetector. Alignment is performed under a microscope to ensure that the LCP / RCP focal points of the liquid crystal dual-focal lens 1 coincide with the centers of the two channels of MoTe2, forming a focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens.

[0037] Step 4, Performance Testing and Results: Test conditions: Light source: 1064 nm laser (tunable power 0.1-5 mW), polarization state adjusted by a quarter-wave plate (QWP).

[0038] Electrical measurements: Keithley 2614B semiconductor parameter analyzer, bias 0.2 V.

[0039] Test results: Rotating the QWP (-90° to +90°), the photocurrent of channel 1 (LCP) increased from... Rise to Channel 2 (RCP) has the opposite response, with an extinction ratio of 82:1. Under linearly polarized light (0°), the photocurrents of the two channels are equal, verifying the absence of polarization bias.

[0040] Photoelectric performance: Responsivity: 120 A / W (0.5 mW, 1064 nm), which is superior to conventional Si detectors (<1 A / W).

[0041] Detection rate: Dark current as low as .

[0042] Response time: rise time 121 ms, fall time 114 ms, e.g. Figure 5 The timing curve is shown.

[0043] Stability test: After 24 hours of continuous operation, the performance fluctuation is less than 5%, indicating the reliability of the device.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0046] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0047] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made by those skilled in the art to the above embodiments within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens, characterized in that, include: A liquid crystal dual-focal lens (1) is used to separate incident circularly polarized light CPL into left-hand circularly polarized light LCP and right-hand circularly polarized light RCP, and to focus the two to different spatial positions. The two-dimensional MoTe2 dual-channel photodetector has a spacing between its two detection channels that matches the focal offset of the liquid crystal bifocal lens (1), and is used to receive LCP and RCP optical signals and perform independent detection, respectively.

2. The focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens according to claim 1, characterized in that: It also includes a Si substrate (6) and a SiO2 dielectric layer (5) formed on the surface of the Si substrate (6). An electrode group (3) including electrode one, electrode two and electrode three is symmetrically arranged on the SiO2 dielectric layer (5). A MoTe2 thin film (4) is provided between electrode one and electrode two. A MoTe2 thin film (4) of the same thickness is provided between electrode two and electrode three. A quartz substrate (2) is provided above the electrode group (3) and the MoTe2 thin film (4). The liquid crystal bifocal lens (1) is provided on the quartz substrate.

3. A focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens according to claim 2, characterized in that: The liquid crystal bifocal lens (1) is based on geometric phase modulation, and its phase distribution satisfies the following formula: ； Where A and B are the relative amplitudes of LCP and RCP, respectively; U LCP and U RCP Let LCP and RCP be the focal light field distributions, respectively, and their expressions are: ； in, Let f be the wave vector, and (x1,y1,f1) and (x2,y2,f2) are the focal positions of LCP and RCP, respectively.

4. A focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens according to claim 1, characterized in that: The channel width of the MoTe2 dual-channel detector is matched with the focusing spot diameter of the liquid crystal bifocal lens (1) to improve photon utilization; the center distance between the two detection channels is consistent with the lateral distance of the focal point of the liquid crystal bifocal lens (1); the thickness of the MoTe2 thin film (4) is 30-35 nm, and the thickness difference between the two channels does not exceed 3 nm to ensure the consistency of photoelectric response.

5. A method for fabricating a focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1, Preparation of a liquid crystal bifocal lens (1): Step 1.1: First, the quartz substrate (2) is ultrasonically cleaned and dried. Then, it is placed in an ultraviolet ozone cleaner to further treat the organic matter on the surface of the quartz substrate (2). Step 1.2: Then spin-coat the SD1 solution onto the surface of the quartz substrate (2) and dry it to evaporate the SD1 solution to obtain the SD1 substrate; Step 1.3: The SD1 substrate is exposed using a DMD micro-exposure system, and a polarization distribution pattern is obtained through multi-step exposure. Step 1.4: Then, the liquid crystal monomers and photoinitiator are spin-coated onto the surface of the SD1 substrate. At this time, the liquid crystal monomers are aligned along the SD1 alignment direction to form the exposed pattern. Step 1.5: After polymerization by UV curing lamp, photoinitiator triggers cross-linking of liquid crystal monomers to form a liquid crystal bifocal lens (1). Step 2: Fabrication of a dual-channel MoTe2 photodetector: Step 2.1: First, the MoTe2 bulk single crystal is peeled off to a few layers (≤50nm) using a special two-dimensional material tape and transferred to the surface of the SiO2 / Si substrate (6); Step 2.2: Locate two MoTe2 films (4) with suitable positions and sizes under a microscope and mark them; Step 2.3: Spin-coat and cure photoresist, construct electrode patterns using laser direct writing, and develop; Step 2.4: Prepare electrode assembly (3) using magnetron sputtering. Step 2.5: Remove excess photoresist from the surface of the Si substrate (6) to obtain a dual-channel MoTe2 photodetector; Step 3, Device Integration and Alignment: The liquid crystal dual-focal lens (1) is integrated on the surface of the dual-channel MoTe2 photodetector and aligned under a microscope to ensure that the LCP / RCP focal points of the liquid crystal dual-focal lens (1) coincide with the centers of the two channels of MoTe2, forming a dual-focal liquid crystal lens-integrated focal plane polarization photodetector.

6. The preparation method according to claim 5, characterized in that: The DMD exposure system has a resolution of 1024×768 pixels and a single micromirror size of 13.68×13.68 μm, enabling high-precision liquid crystal alignment control.

7. The preparation method according to claim 5, characterized in that: The electrode material of the dual-channel MoTe2 photodetector is Au (50 nm) / Ti (5 nm) to reduce contact resistance.

8. The application of a focal plane polarization photodetector with a surface-integrated dual-focal liquid crystal lens as described in any one of claims 1-4, characterized in that: The applications include: Circular polarization state resolution applied in quantum optical communication; Polarization coding detection applied to optical information encryption systems; Detection of optical signals of chiral molecules in biosensing.

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