A middle wave infrared integrated polarization detector and a preparation method thereof

Abstract

The present disclosure provides a middle wave infrared integrated polarization detector and a preparation method. The middle wave infrared integrated polarization detector comprises a plurality of polarization gratings arranged in a periodic array, a dielectric film layer and a middle wave infrared detection chip arranged in sequence. The middle wave infrared detection chip has a plurality of pn junction regions arranged in a periodic array. The pn junction regions are arranged one by one corresponding to the polarization gratings. The middle wave infrared detection chip has a plurality of isolation grooves. The isolation grooves are arranged between adjacent two polarization gratings. The isolation grooves are filled with isolation pieces. By arranging the isolation pieces in the middle wave infrared detection chip, the polarization light crosstalk of adjacent two polarization gratings is suppressed, and the extinction ratio of the middle wave infrared integrated polarization detector is improved. The preparation method of the present disclosure uses nanoimprint technology to directly process nanoscale polarization gratings on the dielectric film layer, which can improve the processing efficiency and reduce the processing cost.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of infrared detectors, and particularly relate to a medium-wave infrared integrated polarization detector and a preparation method thereof. Background Art

[0002] Infrared polarization detection technology can detect polarization information in addition to light intensity, including degree and angle of polarization. It uses the difference in polarization properties between the target and the background to identify the target. Compared to intensity and wavelength detection, polarization imaging is more adaptable to complex environments such as underwater and foggy conditions, as well as camouflaged scenes. In situations where valid target information is absorbed or scattered, polarization detection can effectively suppress background noise and interfering signals, improving target detection accuracy. Medium-wave infrared polarization detection, due to its high sensitivity and strong anti-interference properties, has important applications in military reconnaissance, industrial inspection, and other fields.

[0003] Traditional polarization imaging detection mainly includes time-sharing detection, amplitude-sharing detection, aperture-sharing detection, and focal plane detection. Among them, focal plane detection can obtain information of multiple polarization components at the same time, and the focal plane polarization structure is easy to integrate with the detector, with the advantages of high integration and high stability. Reference [1] Li Junyu, Yi Fei, et al., A dual-color polarization uncooled infrared detector and its manufacturing method, CN111947789B, 2021. The document discloses a structure of an integrated polarization infrared detector, in which the grating and the detector pixel are directly integrated to form a super-pixel structure to realize polarization detection. Reference [2] Junyang Zhang, Zhendong Gao, et al., “Opto-electrical and polarization performance of a mesa-structured InGaAs PIN detector integrated with subwavelength aluminum gratings”, Optics Letters, 47(30), 2022: 6173. (Zhang Junyang, Gao Zhendong, et al., “Opto-electrical and polarization performance of a mesa-structured InGaAs PIN detector integrated with subwavelength aluminum gratings”, Optics Express, 47(30), 2022, p. 6173.) The reference gives an integrated polarization detector structure similar to that of reference [1], in which the Al grating is directly integrated on the InGaAs detector pixel, and the polarization grating is processed by EBL process, achieving an extinction ratio of 18:1 at an operating wavelength of 1550 nm.

[0004] Directly fabricating polarization micro-nano gratings on detector pixels offers excellent stability and high alignment accuracy. By reducing the spacing between the polarization grating and the detector's photosensitive pixel units, optical crosstalk can be reduced, thereby improving the extinction ratio. This is a current research hotspot for integrated polarization detectors, and numerous reports have been published in the visible and near-infrared bands. However, when it comes to mid-wave infrared polarization detectors, especially cooled ones, the high sensitivity of detection leads to significant crosstalk between adjacent polarization pixels, necessitating urgent solutions to the following problems: First, due to the diffraction effect of the polarization grating pixels, crosstalk between adjacent pixels is significant, limiting the extinction ratio of the integrated polarization detector. Second, to achieve a higher extinction ratio, the period of the polarization grating needs to be further reduced, making the process more difficult. Currently, the EBL process is typically used for processing fine polarization gratings, resulting in extremely low processing efficiency and high cost, limiting the widespread application of high-performance integrated polarization detectors. Summary of the Invention

[0005] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art and provide a medium-wave infrared integrated polarization detector and a preparation method thereof.

[0006] A first aspect of the present disclosure provides a medium-wave infrared integrated polarization detector, which includes a plurality of polarization gratings arranged in a periodic array, a dielectric film layer, and a medium-wave infrared detection chip. The medium-wave infrared detection chip has a plurality of pn junction regions arranged in a periodic array, and the pn junction regions are arranged in a one-to-one correspondence with the polarization gratings. The medium-wave infrared detection chip has a plurality of isolation grooves, and the isolation grooves are correspondingly arranged between two adjacent polarization gratings. The isolation grooves are filled with isolation members.

[0007] In some embodiments of the present disclosure, the isolation groove extends from a side of the medium-wave infrared detection chip close to the dielectric film layer to a side away from the dielectric film layer.

[0008] In some embodiments of the present disclosure, the isolation member is in contact with the dielectric film layer.

[0009] In some embodiments of the present disclosure, the depth of the isolation trench is 5 μm, and the width of the isolation trench is 4 μm.

[0010] In some embodiments of the present disclosure, the isolation member is made of zinc sulfide.

[0011] In some embodiments of the present disclosure, four adjacent polarization gratings form a super-pixel, and the four polarization gratings in the super-pixel have different directions.

[0012] In some embodiments of the present disclosure, the polarization grating comprises 62 grating units arranged in a periodic array, the period of the grating units is 400 nm, the line width of the grating units is 200 nm, the size of the polarization grating is 25 μm x 25 μm, and the distance between adjacent two polarization gratings is 30 μm.

[0013] In some embodiments of the present disclosure, the middle-wave infrared detection chip further comprises a plurality of pn junction regions arranged in a periodic array, the pn junction regions extend from the side of the middle-wave infrared chip away from the dielectric film layer to the side close to the dielectric film layer, each of the pn junction regions corresponds to one of the polarization gratings, and the isolation member is located between adjacent two of the pn junction regions.

[0014] In some embodiments of the present disclosure, the material of the dielectric film layer is zinc sulfide, the material of the polarization grating is aluminum, and the material of the middle-wave infrared detection chip is mercury cadmium telluride.

[0015] The second aspect of the present disclosure provides a preparation method of a middle-wave infrared integrated polarization detector, for preparing the middle-wave infrared integrated polarization detector according to any one of the above embodiments, the preparation method comprising:

[0016] preparing a middle-wave infrared detection chip comprising a plurality of pn junction regions;

[0017] preparing a plurality of isolation grooves on the side of the middle-wave infrared detection chip away from the pn junction regions, and filling zinc sulfide in the isolation grooves to form an isolation member;

[0018] preparing a dielectric film layer on the side of the middle-wave infrared detection chip away from the pn junction regions;

[0019] preparing a polarization grating on the side of the dielectric film layer away from the middle-wave infrared detection chip by using a nanoimprint technology;

[0020] flip-chip bonding the side of the pn junction region of the middle-wave infrared detection chip with a readout circuit to form a middle-wave infrared integrated detector.

[0021] The medium-wave infrared integrated polarization detector and preparation method of the embodiment of the present disclosure include a plurality of polarization gratings arranged in a periodic array, a dielectric film layer and a medium-wave infrared detection chip, the polarization grating is used to receive infrared incident light to obtain and emit light intensity signals of different polarization directions in the infrared incident light. The dielectric film layer arranged between the polarization grating and the medium-wave infrared detection chip is used to allow more infrared incident light passing through the polarization grating to reach the medium-wave infrared detection chip. The medium-wave infrared detection chip receives the light intensity signal transmitted through the dielectric film layer, converts the light intensity signal into a current signal and outputs it. The plurality of polarization gratings arranged in a periodic array are arranged in a one-to-one correspondence with the plurality of pn junction regions arranged in a periodic array. The medium-wave infrared detection chip has a plurality of isolation grooves, which are correspondingly arranged between two adjacent polarization gratings, and each isolation groove is filled with an isolation member. By arranging the isolation member in the medium-wave infrared detection chip, the polarization crosstalk of the two adjacent polarization gratings is suppressed, and the extinction ratio of the medium-wave infrared integrated polarization detector is improved. The preparation method of this embodiment uses nanoimprint technology to directly process nanoscale polarization gratings on a dielectric film layer, which can improve processing efficiency and reduce processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the medium-wave infrared integrated polarization detector according to an embodiment of the present disclosure;

[0023] Figure 2 for Figure 1 A cross-sectional view of the mid-wave infrared integrated polarization detector is shown;

[0024] Figure 3 for Figure 1 A top view of the mid-wave infrared integrated polarization detector is shown;

[0025] Figure 4 for Figure 1 A partial cross-sectional view of the mid-wave infrared integrated polarization detector is shown;

[0026] Figure 5 for Figure 1 A comparison of the transmittance curves of single-pixel TM light of a medium-wave infrared integrated polarization detector and a medium-wave infrared integrated polarization detector without an isolator is shown;

[0027] Figure 6 for Figure 1 A comparison of the transmittance curves of single-pixel TE light of a medium-wave infrared integrated polarization detector and a medium-wave infrared integrated polarization detector without an isolator is shown;

[0028] Figure 7 for Figure 1 A comparison diagram of the extinction ratio of a single pixel of a medium-wave infrared integrated polarization detector and a medium-wave infrared integrated polarization detector without an isolation element is shown;

[0029] Figure 8 This is a flow chart of a method for preparing a medium-wave infrared integrated polarization detector according to an embodiment of the present disclosure;

[0030] Figure 9 The present invention is a flowchart of the specific steps of the method for preparing the medium-wave infrared integrated polarization detector according to the embodiment of the present invention.

[0031] The reference numerals in the accompanying drawings represent the following:

[0032] 100, polarization grating; 100A, metal film; 101, second adhesive layer;

[0033] 200, dielectric film layer;

[0034] 300, medium-wave infrared detection chip; 301, isolation element; 301A, deep trench; 301B, zinc sulfide layer; 302, pn junction region; 303, first adhesive layer;

[0035] 400, readout circuit;

[0036] 500, indium column;

[0037] 600. Infrared incident light. DETAILED DESCRIPTION

[0038] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0039] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0040] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0041] For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures, such as "inside," "outside," "inside," "outside," "below," "beneath," "above," and the like. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is flipped, an element described as "below" or "beneath" another element or feature would then be oriented as "above" or "above" the other element or feature. Thus, the example term "below" can encompass both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein are interpreted accordingly.

[0042] like Figures 1 to 4 As shown, the first aspect of the present disclosure provides a medium-wave infrared integrated polarization detector, which includes a plurality of polarization gratings 100 arranged in a periodic array, a dielectric film layer 200 and a medium-wave infrared detection chip 300 arranged in sequence. The medium-wave infrared detection chip 300 has a plurality of pn junction regions 302 arranged in a periodic array, and the pn junction regions 302 are arranged in a one-to-one correspondence with the polarization gratings 100. The medium-wave infrared detection chip 300 has a plurality of isolation grooves, and the isolation grooves are correspondingly arranged between two adjacent polarization gratings 100. The isolation grooves are filled with isolation members 301.

[0043] The middle wave infrared integrated polarization detector according to the present disclosure comprises a plurality of polarization gratings 100, a dielectric film layer 200 and a middle wave infrared detection chip 300 arranged in sequence, the polarization gratings 100 are used for receiving infrared incident light 600 to obtain and emit light intensity signals of different polarization directions in the infrared incident light 600, the dielectric film layer 200 arranged between the polarization gratings 100 and the middle wave infrared detection chip 300 is used for making more infrared incident light 600 passing through the polarization gratings 100 to reach the middle wave infrared detection chip 300, the middle wave infrared detection chip 300 receives the light intensity signals passing through the dielectric film layer 200 and converts the light intensity signals into current signals and outputs the current signals. The plurality of polarization gratings 100 arranged in a periodic array correspond to the plurality of pn junction regions 302 arranged in a periodic array one by one. The middle wave infrared detection chip 300 has a plurality of isolation grooves, the isolation grooves are arranged between adjacent two polarization gratings 100, and each isolation groove is filled with an isolation piece 301. By arranging the isolation piece 301 in the middle wave infrared detection chip 300, the polarization light crosstalk of the adjacent two polarization gratings 100 is suppressed, and the extinction ratio of the middle wave infrared integrated polarization detector is improved.

[0044] In some embodiments of the present disclosure, the plurality of polarization gratings 100 are arranged in a periodic array, wherein four adjacent polarization gratings 100 form a super-pixel, and the four polarization gratings 100 of the super-pixel are different in direction. Specifically, the four polarization gratings 100 of the super-pixel can be polarization gratings 100 of 0°, 45°, 90° and 135° directions respectively. The four polarization gratings 100 of the super-pixel can also be polarization gratings 100 of other four directions.

[0045] In some embodiments of the present disclosure, the polarization grating 100 comprises 62 grating units arranged in a periodic array, the period of the grating unit is 400 nm, the line width of the grating unit is 200 nm, the size of the polarization grating 100 is 25 μm×25 μm, and the center distance between adjacent two polarization gratings 100 is 30 μm. Specifically, the material of the polarization grating 100 is aluminum. The aluminum material polarization grating 100 has the characteristics of wide spectrum response, high environmental stability, light weight and low cost.

[0046] In some embodiments of the present disclosure, the mid-wave infrared detection chip 300 further comprises a plurality of pn junction regions 302 arranged in a periodic array. The pn junction regions 302 extend from the side of the mid-wave infrared chip facing away from the dielectric film layer 200 to the side closer to the dielectric film layer 200. Each pn junction region 302 corresponds to a polarization grating 100. The projection of the isolation member 301 on the bottom surface of the mid-wave infrared detection chip 300 facing away from the dielectric film layer 200 is located between two adjacent pn junction regions 302. Specifically, the mid-wave infrared detection chip 300 is made of mercury cadmium telluride (HgCdTe). Mercury cadmium telluride (HgCdTe) offers the advantages of high sensitivity, wide spectral tunability, fast response, and radiation resistance.

[0047] In some embodiments of the present disclosure, the isolation trench extends from the side of the medium-wave infrared detection chip 300 close to the dielectric film layer 200 to the side away from the dielectric film layer 200. That is, the isolation trench extends along the thickness direction of the medium-wave infrared detection chip 300, so that the isolation member 301 extends from the side of the medium-wave infrared detection chip 300 close to the dielectric film layer 200 to the side of the pn junction region 302 of the medium-wave infrared detection chip 300. The isolation member 301 extends along the thickness direction of the medium-wave infrared detection chip 300 to suppress crosstalk between the polarized light of two adjacent polarization gratings 100 in the medium-wave infrared detection chip 300.

[0048] Specifically, the isolation groove extends from the surface of the MWIR detection chip 300 that contacts the dielectric film layer 200 to the surface facing away from the dielectric film layer 200. That is, one end of the isolation member 301 contacts the dielectric film layer 200, while the other end of the isolation member 301 extends into the interior of the MWIR detection chip 300. Specifically, the isolation member 301 is made of the same material as the dielectric film layer 200: zinc sulfide. Zinc sulfide isolation members 301 possess wide-band optical transmittance, a high refractive index, and excellent electrical isolation.

[0049] In some embodiments of the present disclosure, the depth of the isolation trench refers to the dimension of the isolation trench along the thickness direction of the medium-wave infrared detection chip 300. Specifically, the depth of the isolation trench is 5 μm. The width of the isolation trench refers to the dimension of the isolation trench along the direction from the polarization grating 100 closest to one side of the isolation trench to the polarization grating 100 closest to the other side of the isolation trench. Specifically, the width of the isolation trench is 4 μm. The length of the isolation trench is greater than or equal to the side length of the polarization grating 100.

[0050] like Figure 5 As shown in FIG, the transmittance of the single pixel TM light does not change much before and after adding the spacer 301, but increases slightly after adding the spacer 301. Figure 6 As shown in FIG, the transmittance of the TE light of a single pixel changes significantly after the spacer 301 is added. After the spacer 301 is added, the transmittance of the TE light decreases. Combining the changes in the transmittance of the TM light and the TE light, as shown in FIG. Figure 7As shown, after the spacer 301 is added, the extinction ratio is greatly improved compared to before the spacer 301 is added. It can be seen that adding the spacer 301 in the middle-wave infrared detection chip 300 can improve the extinction ratio.

[0051] As shown in Figure 8 , Figure 9 The second aspect of the present disclosure provides a preparation method of a middle-wave infrared integrated polarization detector, for preparing the middle-wave infrared integrated polarization detector according to any one of the above embodiments, the preparation method comprising:

[0052] S100: preparing a middle-wave infrared detection chip 300 containing a plurality of pn junction regions 302;

[0053] S200: preparing a plurality of isolation grooves on the side of the middle-wave infrared detection chip 300 away from the pn junction region 302, and filling zinc sulfide in the isolation grooves to form a spacer 301;

[0054] S300: preparing a dielectric film layer 200 on the side of the middle-wave infrared detection chip 300 away from the pn junction region 302;

[0055] S400: preparing a polarization grating 100 on the side of the dielectric film layer 200 away from the middle-wave infrared detection chip 300 by using a nanoimprint technology;

[0056] S500: flip-chip bonding the side of the pn junction region 302 of the middle-wave infrared detection chip 300 with a readout circuit 400 to form a middle-wave infrared integrated detector.

[0057] The preparation method of the middle-wave infrared integrated polarization detector according to the present disclosure first prepares a middle-wave infrared detection chip 300 containing a plurality of pn junction regions 302, and then prepares a plurality of isolation grooves on the side of the middle-wave infrared detection chip 300 away from the pn junction region 302, so as to fill zinc sulfide in the isolation grooves to form a spacer 301 made of zinc sulfide. Then, a dielectric film layer 200 is prepared on the side of the middle-wave infrared detection chip away from the pn junction region 302. Then, a polarization grating 100 is prepared on the side of the dielectric film layer 200 away from the middle-wave infrared detection chip 300 by using a nanoimprint technology. Finally, the side of the pn junction region 302 of the middle-wave infrared detection chip 300 is flip-chip bonded with a readout circuit 400 to form a middle-wave infrared integrated detector. The preparation method of the present embodiment uses a nanoimprint technology to directly process a nanoscale polarization grating 100 on the dielectric film layer 200, which can improve the processing efficiency and reduce the processing cost. In addition, the middle-wave infrared detection chip 300 prepared by the preparation method of the present embodiment is provided with a spacer 301, which can suppress the polarization light crosstalk between adjacent two polarization gratings 100 and improve the extinction ratio of the middle-wave infrared integrated polarization detector.

[0058] The specific steps of the method for preparing the medium-wave infrared integrated polarization detector in this embodiment are as follows:

[0059] Step (1) Glue coating: preparing a medium-wave infrared detection chip 300 containing a pn junction region 302, and spin-coating a first glue layer 303 on some areas away from the pn junction region 302 of the medium-wave infrared detector chip. Specifically, the material of the first glue layer 303 is ultraviolet photoresist.

[0060] Step (2) Patterning: The first glue layer 303 spun in step (1) is patterned, that is, the photoresist in the first glue layer 303 is exposed, and then the unnecessary glue is washed away by a development process, and then the required photoresist pattern is formed on the first glue layer 303 through a fixing and drying process. The photoresist pattern is a grid-shaped deep groove 301A. Specifically, the width of the deep groove 301A is 4 μm.

[0061] Step (3) etching: After the patterning in step (2) is completed, the obtained structure is sent to an etcher for etching to obtain isolation grooves 301A arranged in a grid pattern, with a depth of 5 μm and a width of 4 μm.

[0062] Step (4) Filling the isolation groove with ZnS: After etching in step (3), the obtained structure is placed in a coating machine to deposit a 4 μm thick zinc sulfide layer 301B, and zinc sulfide is filled in the isolation groove 301A to obtain the isolation member 301.

[0063] Step (5) debonding: After the isolation groove 301A is filled in step (4), the obtained overall structure is placed in an acetone solution for cleaning to remove the first glue layer 303 remaining on the surface of the medium-wave infrared detection chip 300, thereby obtaining a medium-wave infrared detector chip containing a zinc sulfide isolation member 301.

[0064] Step (6) ZnS coating: After completing step (5), a zinc sulfide film is deposited on one side of the isolation member 301 of the medium-wave infrared detector chip as a dielectric film layer 200. The dielectric film layer 200 has a thickness of 500 nm and has a transmittance-enhancing effect on 3-5 μm infrared incident light 600.

[0065] Step (7) Al coating: a metal film 100A made of aluminum is magnetron sputtered on the zinc sulfide film, i.e., the dielectric film layer 200. The thickness of the aluminum film 100A is 100 nm. The thickness of the aluminum film 100A layer only needs to exceed the metal skin depth, i.e., more than tens of nanometers.

[0066] Step (8) Glue coating: spin-coating a second glue layer 101 on the metal film 100A of the medium-wave infrared detector chip after coating. The material of the second glue layer 101 is nano-imprint glue.

[0067] Step (9) patterning: the second glue layer 101 coated in step (8) is subjected to patterning treatment, that is, the nanoimprint glue in the second glue layer 101 is subjected to imprinting, the template is contacted with the second glue layer 101 coated, the pattern is transferred to the nanoimprint glue by pressing, then the pattern is cured by irradiation with ultraviolet light, finally the pressure is released, the template is separated from the second glue layer 101 in which the pattern of the nanoimprint glue is formed, and a plurality of structures arranged in a periodic array are obtained.

[0068] Step (10) etching: after the patterning is completed, the obtained structure is sent into an etching machine for etching, and a plurality of polarization gratings 100 arranged in a periodic array are obtained. The polarization grating 100 includes a plurality of grating units, the grating unit period is 400 nm, the grating unit line width is 200 nm, and the grating unit length is 25 μm. The size of the polarization grating 100 is 25 μm x 25 μm, and the spacing between adjacent polarization gratings 100 is 5 μm. The polarization grating 100 and the photosensitive pixel of the mid-wave infrared detection chip 300 are one-to-one corresponding, and the adjacent four polarization gratings 100 constitute a super-pixel. The directions of the four polarization gratings 100 in the super-pixel are different, which are 0°, 45°, 90° and 135° respectively.

[0069] Step (11) glue removal: after the etching is completed, the obtained grating structure is placed in an acetone solution for cleaning, and the residual second glue layer 101 on the polarization grating 100 is removed, so that all surfaces of each polarization grating 100 except the side in contact with the dielectric film layer 200 are exposed to air, and the structure of the nanoscale polarization grating 100 is obtained.

[0070] Step (12) flip-chip bonding: after the glue removal is completed, the side of the mid-wave infrared detection chip 300 away from the polarization grating 100 is connected with the readout circuit 400 by the flip-chip bonding process through the indium column 500, and the mid-wave infrared integrated polarization detector is obtained.

[0071] It can be understood that the above embodiments are only exemplary embodiments adopted for illustrating the principles of the present disclosure, but the present disclosure is not limited thereto. Various modifications and improvements can be made by those of ordinary skill in the art without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also regarded as the protection scope of the present disclosure.

Claims

1. A medium-wave infrared integrated polarization detector, characterized in that: The medium-wave infrared integrated polarization detector includes a plurality of polarization gratings, a dielectric film layer, and a medium-wave infrared detection chip arranged in sequence in a periodic array. The medium-wave infrared detection chip has a plurality of pn junction regions arranged in a periodic array, and the pn junction regions are arranged in a one-to-one correspondence with the polarization gratings. The medium-wave infrared detection chip has a plurality of isolation grooves, each of which is correspondingly arranged between two adjacent polarization gratings. The isolation grooves extend from a side of the medium-wave infrared detection chip close to the dielectric film layer to a side away from the dielectric film layer, and the isolation grooves are filled with isolation members. The isolation member is in contact with the dielectric film layer, and the isolation member extends from the dielectric film layer toward the pn junction region inside the medium-wave infrared detection chip, and the isolation member and the dielectric film layer are both made of zinc sulfide; The depth of the isolation trench is 5 μm, and the width of the isolation trench is 4 μm.

2. The medium-wave infrared integrated polarization detector according to claim 1, characterized in that: Four adjacent polarization gratings form a super pixel, and the directions of the four polarization gratings in the super pixel are different.

3. The medium-wave infrared integrated polarization detector according to claim 1, characterized in that: The polarization grating includes 62 grating units arranged in a periodic array, the period of the grating unit is 400 nm, the line width of the grating unit is 200 nm, the size of the polarization grating is 25 μm×25 μm, and the spacing between two adjacent polarization gratings is 30 μm.

4. The medium-wave infrared integrated polarization detector according to claim 1, characterized in that: The medium-wave infrared detection chip also has multiple pn junction regions arranged in a periodic array, and the pn junction regions extend from the side of the medium-wave infrared chip away from the dielectric film layer to the side close to the dielectric film layer. Each of the pn junction regions corresponds to one of the polarization gratings.

5. The medium-wave infrared integrated polarization detector according to claim 1, characterized in that: The material of the polarization grating is aluminum, and the material of the medium-wave infrared detection chip is mercury cadmium telluride.

6. A method for preparing a medium-wave infrared integrated polarization detector, for preparing a medium-wave infrared integrated polarization detector according to any one of claims 1 to 5, characterized in that: The preparation method comprises: preparing a medium-wave infrared detection chip containing multiple pn junction regions; A plurality of isolation trenches are prepared on a side of the medium-wave infrared detection chip away from the pn junction region, and zinc sulfide is filled in the isolation trenches to form isolation members; A dielectric film layer is formed on a side of the medium-wave infrared detection chip away from the pn junction region; A polarization grating is fabricated on the side of the dielectric film layer facing away from the mid-wave infrared detection chip using nanoimprint technology. One side of the pn junction region of the medium-wave infrared detection chip is flip-chip soldered to the readout circuit to form a medium-wave infrared integrated detector.

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