Free operation single photon detector with high integration level

Abstract

The invention discloses a free operation single photon detector, which comprises a shell (1), a radiator module (2), a PCB (3), a shielding case module (4) and a secondary refrigeration module (5), the radiator module (2), the PCB (3), the shielding case module (4) and the secondary refrigeration module (5) are all wrapped in the shell (1), the PCB (3) is fixed above the radiator module (2), the PCB (3) is clamped in the middle of the shielding case module (4), and the shielding case module (4) is fixed on the shell (1). The bottom opening of the shielding cover module (4) is fixed on the upper surface of the radiator module (2), the clamped part of the PCB (3) is provided with an opening, the secondary refrigeration module (5) is placed at the middle opening of the PCB (3), and the bottom surface of the secondary refrigeration module (5) is in contact with the radiating surface of the radiator module (2). The PCB is clamped in the middle of the shielding cover module, the bottom opening of the shielding cover module is fixed to the upper surface of the radiator, the structural design is ingenious, and the overall integration degree is high.

Description

Technical Field

[0001] This patent belongs to the field of optoelectronic detection devices, and specifically relates to a free-running single-photon detector. Background Art

[0002] Currently, negative-feedback avalanche diodes (NFADs) are commonly used as the core detection devices in free-running single-photon detection technology, which can achieve rapid quenching of the avalanche current and suppress after-pulse effects, providing solutions for asynchronous weak-light detection applications such as quantum communication, lidar, and fluorescence lifetime detection.

[0003] During operation, the lower the ambient temperature of the NFAD, the better the detection efficiency. However, traditional thermoelectric coolers (TECs) require a large amount of power to reach the low-temperature refrigeration target, and the heat exchange efficiency between devices is relatively low, resulting in limited detection efficiency.

[0004] Chinese Patent "Refrigeration Device and Equipment for Single-Photon Detectors" with Application No. CN202220549806.6 discloses a refrigeration device and equipment for single-photon detectors, including a heat sink, a multi-layer thermoelectric cooler TEC, a heat conduction film, and a photodetector. Among them, a through-hole for placing a single-photon detector is provided inside the heat sink; the multi-layer thermoelectric cooler TEC includes N layers of thermoelectric coolers TEC; the inside of the heat conduction film is hollow and is fixedly arranged on the top of the multi-layer thermoelectric cooler TEC; one end of the photodetector is fixedly arranged inside the heat sink, effectively utilizing the cold surface of the first-layer thermoelectric cooler in the multi-layer thermoelectric cooler TEC to effectively cool the single-photon detector and ensure the stability of the performance of the single-photon detector. However, the devices in this refrigeration device are separated from each other and connected individually, with poor fastening effect. During actual use, the devices may become loose or even separate from each other; during rapid refrigeration, the surface of the pin parts of the photodetector and the single-photon detector is lower than the ambient temperature, and when humid ambient air encounters a surface below the dew point, water vapor will condense to form dew, resulting in a reduction in the working efficiency of the device or even failure, reducing the service life of the equipment.

[0005] The Chinese patent "A Refrigeration Structure and a Single Photon Detection Device" with the application number CN202010244596.5 discloses a refrigeration box structure, which includes a plurality of refrigeration boxes arranged side by side. Each refrigeration box is individually encapsulated and includes a radiator, a housing, a TEC cooler, a bias plate, an APD tube (avalanche photodiode), and an optical fiber connector. The TEC cooler, the bias plate, and the APD tube are fixed inside the housing, the radiator is fixed outside the housing, and the optical fiber connector extends into the interior of the refrigeration box through an optical fiber connection hole for connecting the optical fiber of the APD tube inside the refrigeration box and the transmission optical fiber outside the refrigeration box. By arranging a plurality of refrigeration boxes side by side to form a refrigeration structure, when a certain channel fails, only the corresponding refrigeration box needs to be removed and repaired, without affecting other channels, improving the stability of the product.

[0006] However, the core device of this device uses a traditional APD tube, and the heat dissipation method is through heat transfer by contact between the tube wall and the tube clamp, resulting in poor heat exchange effect; at the same time, when using an APD tube, it is necessary to weld the pins to the circuit board, which requires a certain amount of space for operation, resulting in a large space occupied by the detection device and low integration. Summary of the Invention

[0007] The technical problem to be solved by the present invention is how to improve the integration of a free-running single photon detector.

[0008] The present invention solves the above technical problems through the following technical means: A free-running single photon detector with high integration, including a housing (1), a radiator module (2), a PCB board (3), a shielding cover module (4), and a secondary refrigeration module (5). The radiator module (2), the PCB board (3), the shielding cover module (4), and the secondary refrigeration module (5) are all enclosed in the housing (1). The PCB board (3) is fixed above the radiator module (2), the PCB board (3) is clamped in the middle of the shielding cover module (4), the bottom of the shielding cover module (4) is empty and fixed on the upper surface of the radiator module (2), and an opening is provided in the clamped part of the PCB board (3). The secondary refrigeration module (5) is placed at the middle opening of the PCB board (3) and the bottom surface is in contact with the heat dissipation surface on the radiator module (2).

[0009] As an optimized technical solution, the housing (1) is a square housing (1) jointly formed by a front panel (1-A), a rear panel (1-C), a ring frame (1-B), and an upper cover (1-D).

[0010] As an optimized technical solution, the PCB board (3) passes through the shielding cover module (4) and divides the shielding cover module (4) into upper and lower parts. The upper part circuit module of the PCB board (3) is clamped in the middle of the shielding cover module (4).

[0011] As an optimized technical solution, the shielding cover module (4) is located at a corner of the radiator module (2). The upper end of the radiator module (2) extends out the mounting posts (202), and the PCB board (3) is fixed on the mounting posts (202). There are 3 mounting posts (202), and a corner of the PCB board (3) not fixed on the mounting posts (202) is supported and fixed by the shielding cover module (4).

[0012] As an optimized technical solution, the radiator module (2) further includes protruding stud structures (203) that come into contact with the high-heat chips on the PCB board (3).

[0013] As an optimized technical solution, the radiator module (2) includes a radiator (2-A) and a fan (2-B). Multiple threaded holes (201) are provided on the side of the radiator (2-A), and the screws pass through the mounting holes of the fan (2-B) and are fixed in the threaded holes (201) to achieve the installation of the fan (2-B).

[0014] As an optimized technical solution, a cavity is provided at the position of the radiator (2-A) corresponding to the installation of the fan (2-B), and the fan (2-B) is integrally recessed into the radiator (2-A).

[0015] As an optimized technical solution, the secondary cooling module (5) is wrapped in the enclosed space formed by the shielding cover module (4).

[0016] As an optimized technical solution, the material of the shielding cover module (4) is aluminum alloy, and the internal space of the shielding cover module (4) is filled with foam at the same time.

[0017] As an optimized technical solution, the secondary cooling module (5) includes an NFAD (5-A), a copper block base (5-B), a plastic pressing block (5-C), and multiple layers of TEC (5-D) arranged in sequence from top to bottom. The shape of the opening of the PCB board (3) matches the shape of the NFAD (5-A), and the NFAD (5-A) is welded to the PCB board (3). The NFAD (5-A) is located in the upper cavity of the shielding cover module (4). The copper block base (5-B), the plastic pressing block (5-C), and the multiple layers of TEC (5-D) are fixed together and located in the lower cavity of the shielding cover module (4). The NFAD (5-A) is fixed by the copper block base (5-B) located below the PCB board (3), and its optical fiber tail end passes through the optical fiber hole (406) provided at the bottom side of the shielding cover module (4). After being fixed, the gap of the optical fiber hole (406) is filled with glue.

[0018] As an optimized technical solution, the bottom surface of the multi-layer TEC (5-D) is in contact with the upper surface of the radiator (2-A). The plastic pressing block (5-C) is a ring frame, nested around the multi-layer TEC (5-D), and has a groove structure at the bottom to press the bottom layer of the multi-layer TEC (5-D). The plastic pressing block (5-C) is fixed on the surface of the radiator (2-A), and the multi-layer TEC (5-D) is fixedly installed between the radiator (2-A) and the plastic pressing block (5-C). The copper block base (5-B) is fixed on the plastic pressing block (5-C) and is in contact with the top surface of the multi-layer TEC (5-D). The NFAD (5-A) is fixedly installed in the groove opened on the upper surface of the copper block base (5-B).

[0019] As an optimized technical solution, the shielding cover module (4) includes a shielding cover upper cover (4-A), a shielding cover (4-B), and a shielding cover ring frame (4-C). The bottom of the shielding cover module (4) is empty. The shielding cover upper cover (4-A) covers the shielding cover (4-B). The PCB board (3) is clamped between the shielding cover (4-B) and the shielding cover ring frame (4-C). The shielding cover upper cover (4-A) is fixed to the shielding cover (4-B), and the PCB board (3) is fixed to the shielding cover (4-B) and the shielding cover ring frame (4-C). The shielding cover ring frame (4-C) is fixed to the upper surface of the radiator (2-A) through the bosses (405) around the bottom.

[0020] The advantages of the present invention are as follows:

[0021] 1. In the present invention, the PCB board is clamped in the middle of the shielding cover module, and the bottom of the shielding cover module is open and fixed on the upper surface of the radiator. The structure is ingeniously designed and the overall integration degree is high;

[0022] 2. The present invention proposes a shielding cover structure to meet the electromagnetic shielding requirements of high-performance chips on the PCB board;

[0023] 3. The upper end of the radiator extends out the mounting posts, and the PCB board is fixed on the mounting posts. There are actually only 3 mounting posts, and one corner of the PCB board not fixed on the mounting posts is supported and fixed by the shielding cover module, making the installation of the PCB board more stable and increasing the overall integration degree;

[0024] 4. Multiple threaded holes are provided on the side of the radiator, and the screws pass through the mounting holes of the fan and are fixed in the threaded holes to realize the installation of the fan, reducing the number of parts required for installing the fan. And a cavity is provided at the position of the radiator corresponding to the installation of the fan, and the fan is integrally recessed into the radiator, further increasing the overall integration degree;

[0025] 5. A two-stage refrigeration module is designed, and its installation method increases the fastening property of the two-stage refrigeration module.

[0026] 6. In the present invention, an integrated NFAD design is used. The APD chip is integrally welded inside the NFAD without welding pins to the circuit board, eliminating the need to reserve a certain space for operation, and further realizing a miniaturized design. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. 6 is an exploded view of a highly integrated free-running single-photon detector according to an embodiment of the present invention;

[0028] Figure 2 FIG. 10 is an exploded view of the housing according to an embodiment of the present invention;

[0029] Figure 3 FIG. 14 is an internal structure diagram of a highly integrated free-running single-photon detector according to an embodiment of the present invention;

[0030] Figure 4 FIG. 18 is a structural diagram of the heat sink module according to an embodiment of the present invention;

[0031] Figure 5 FIG. 22 is a relative position structural diagram of the shielding cover module, the PCB board, and the secondary refrigeration module according to an embodiment of the present invention;

[0032] Figure 6 FIG. 26 is a structural diagram of the secondary refrigeration module according to an embodiment of the present invention;

[0033] Figure 7 FIG. 30 is an exploded view of the secondary refrigeration module according to an embodiment of the present invention;

[0034] Figure 8 FIG. 34 is a cross-sectional view of the NFAD according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Please refer to Figure 1As shown in the figure, the present invention proposes a free-running single-photon detector with high integration, which includes a housing 1, a radiator module 2, a PCB board 3, a shielding cover module 4, and a secondary refrigeration module 5. The radiator module 2, the PCB board 3, the shielding cover module 4, and the secondary refrigeration module 5 are all enclosed in the housing 1. The PCB board 3 is fixed above the radiator module 2. The PCB board 3 is clamped in the middle of the shielding cover module 4. The bottom of the shielding cover module 4 is empty and fixed on the upper surface of the radiator 2-A. An opening is provided in the clamped part of the PCB board 3. The secondary refrigeration module 5 is placed in the middle opening of the PCB board 3. The overall structure of the secondary refrigeration module 5 is sealed in the shielding cover module 4 and its bottom surface is in contact with the upper heat dissipation surface of the radiator module 2.

[0037] Figure 2 Fig. is an exploded view of the housing 1, where 1-A is the front panel, 1-B is the U-shaped ring frame, 1-C is the rear panel, and 1-D is the upper cover. The front panel 1-A, the rear panel 1-C, the ring frame 1-B, and the upper cover 1-D together form a square housing 1. The positions and numbers of the boss structures on the front panel 1-A and the rear panel 1-C are the same. Specifically, the boss structures 101 at both upper ends and the boss structures 103 at both lower ends on the front panel 1-A, the boss structures (not shown in the figure) at both upper ends and the boss structures (not shown in the figure) at both lower ends on the rear panel 1-C are respectively fixed to the mounting holes 102 (4 pieces) on the upper side of the side plate and the mounting holes 104 (4 pieces) on the lower side of the side plate of the ring frame 1-B by screws. The boss structure 106 on the upper cover 1-D and the mounting holes 105 at both upper ends of the rear panel 1-C are fixed by screws.

[0038] Figure 3 Fig.

[0037] is a structural diagram of the interior of the detector. The PCB board 3 is fixed above the radiator module 2. The shielding cover module 4 is located at a corner of the radiator module 2. The PCB board 3 passes through the shielding cover module 4 and divides the shielding cover module 4 into upper and lower parts. The part of the circuit module where the high-performance chips on the PCB board 3 are located is clamped in the middle of the shielding cover module 4. This design can perform electromagnetic shielding and at the same time assist in supporting and fixing the PCB board 3. The bottom of the shielding cover module 4 is fixed to the upper surface of the radiator module 2 by screws.

[0039] Figure 4 Fig. Figure 2 is a structural diagram of the radiator module 2. The radiator module 2 includes a radiator 2-A and a fan 2-B. After milling, the upper end of the radiator 2-A extends out the mounting post 202. Figure 3The middle PCB board 3 is fixed on the mounting posts 202. Actually, there are only 3 mounting posts 202. One corner of the PCB board 3 that is not fixed on the mounting posts 202 is supported and fixed by the shielding cover module 4. Other protruding stud structures 203 on the radiator 2-A are in contact with the high-heat chips on the PCB board 3 to achieve rapid heat exchange. A plurality of threaded holes 201 are provided on the side of the radiator 2-A. Screws pass through the mounting holes of the fan 2-B and are fixed in the threaded holes 201 to achieve the installation of the fan 2-B, reducing the number of parts required for installing the fan 2-B. Moreover, a cavity is provided at the position of the radiator 2-A corresponding to the installation of the fan 2-B, and the whole fan 2-B is recessed into the radiator 2-A and integrated. The air direction of the fan 2-B corresponds to the fin direction.

[0040] Figure 5 It is a relative position structure diagram of the shielding cover module 4, the PCB board 3, and the secondary refrigeration module 5. The shielding cover module 4 includes a shielding cover upper cover 4-A, a shielding cover 4-B, and a shielding cover ring frame 4-C. The bottom of the shielding cover module 4 is empty. The shielding cover upper cover 4-A covers the shielding cover 4-B. The PCB board 3 is clamped between the shielding cover 4-B and the shielding cover ring frame 4-C. An opening is provided in the clamped part of the PCB board 3, dividing the shielding cover module 4 into upper and lower parts, thus forming upper and lower cavities with an opening in the middle. The upper cavity, i.e., the space contained in the shielding cover 4-B, accommodates the high-performance chips on the PCB board 3.

[0041] Also refer to Figure 6, is the structure diagram of the secondary refrigeration module 5. The secondary refrigeration module 5 is placed at the middle opening of the PCB board 3. The overall structure of the secondary refrigeration module 5 penetrates the upper and lower cavities. The secondary refrigeration module 5 includes an NFAD 5-A, a copper block base 5-B, a plastic pressing block 5-C, and multiple layers of TEC 5-D arranged in sequence from top to bottom. Specifically, the shape of the opening of the PCB board 3 matches the shape of the NFAD 5-A of the secondary refrigeration module 5. The pins on both sides of the NFAD 5-A are soldered to the PCB board 3, so that the NFAD 5-A is located in the upper cavity, that is, the shielding cover 4-B. The copper block base 5-B, the plastic pressing block 5-C, and multiple layers of TEC 5-D are fixed together and located in the lower cavity, that is, the shielding cover ring frame 4-C. The NFAD 5-A is fixed through the copper block base 5-B located below the PCB board 3, and its optical fiber tail end is thrown out through the optical fiber hole 406 at the bottom side of the shielding cover ring frame 4-C. After fixing, the gap of the optical fiber hole 406 is filled with glue to make the overall structure of the shielding cover module 4 form a closed space. The shielding cover upper cover 4-A and the shielding cover 4-B are fixed with screws through the mounting holes 401 and 402 (four each). The PCB board 3 is fixed with screws through the mounting holes 407 on it and the mounting holes 403 (four each) on the upper shielding cover 4-B and the mounting holes 404 (four each) on the lower shielding cover ring frame 4-C. The shielding cover ring frame 4-C is fixed on the upper surface of the radiator 2-A through the bosses 405 around the bottom. The material of the shielding cover module 4 is aluminum alloy, and the structural design meets the electromagnetic shielding requirements of high-performance chips on the PCB board 3. At the same time, the internal space of the shielding cover module 4 is filled with foam, and the secondary refrigeration module 5 is wrapped in the closed space formed by the shielding cover module 4 to prevent the device from being exposed to the air, effectively solving the condensation problem caused by rapid refrigeration.

[0042] Figure 7 Is the exploded view of the secondary refrigeration module 5. Also refer to Figure 1 And Figure 4 , the installation method of the secondary refrigeration module 5 can increase the installation stability of the secondary refrigeration module 5. The specific installation method is as follows:

[0043] STEP1: The bottom surface of the multiple layers of TEC 5-D contacts the upper surface of the radiator 2-A, which can conduct the heat of the bottom hot surface to the radiator 2-A to achieve a rapid heat exchange effect;

[0044] STEP2: The plastic pressing block 5-C can be designed as a ring frame and nested around the multiple layers of TEC 5-D. At the same time, a groove structure is provided at the bottom, which can press the bottom layer of the multiple layers of TEC 5-D. Through holes 504 are opened at the four corners of the plastic pressing block 5-C. After the screws pass through the through holes 504, they are fixed on the surface mounting holes of the radiator 2-A, and the multiple layers of TEC 5-D are fixedly installed between the radiator 2-A and the plastic pressing block 5-C;

[0045] STEP 3: The copper block base 5-B is located above the plastic pressing block 5-C and is in contact with the top surface of the multi-layer TEC 5-D. The copper block base 5-B and the plastic pressing block 5-C share the same set of mounting through holes 503 and 504 (four each). The copper block base 5-B is fixed to the plastic pressing block 5-C by screws and presses the top surface of the multi-layer TEC 5-D;

[0046] STEP 4: The NFAD 5-A is located above the copper block base 5-B. A groove is provided on the upper surface of the copper block base 5-B, and threaded holes 502 for fixing the NFAD 5-A are provided at the four corners of the groove. The NFAD 5-A is placed in the groove of the copper block base 5-B, and the NFAD 5-A is fixedly installed on the copper block base 5-B by screws passing through the mounting holes 501 of the NFAD 5-A. Copper has high heat exchange efficiency, and at the same time, the contact area of the hot surface of the NFAD 5-A is increased.

[0047] See Figure 8 , which is a cross-sectional view of the NFAD 5-A. The NFAD 5-A includes an optical fiber 5-A-1, a chip 5-A-2, a temperature sensor 5-A-3, an internal TEC 5-A-4, and a housing 5-A-5. The optical fiber 5-A-1 and the internal TEC 5-A-4 are fixed on the housing 5-A-5. The chip 5-A-2 is arranged on the cold surface of the internal TEC 5-A-4. The temperature sensor 5-A-3 is located on the chip 5-A-2 and is connected to the chip 5-A-2. The temperature sensor 5-A-3 is used to monitor the internal temperature condition of the NFAD 5-A and transmit signals to the chip 5-A-2 for temperature control.

[0048] The multi-stage refrigeration strategy of the free-running single-photon detector designed by the present invention is as follows: The internal TEC 5-A-4 of the NFAD 5-A can achieve the first-stage refrigeration of the NFAD 5-A, avoiding low-efficiency heat exchange in a contact manner; by controlling the direction and magnitude of the current of the multi-layer TEC 5-D, a second-stage refrigeration effect can be achieved on the basis of the first-stage refrigeration inside the NFAD 5-A itself; a single fan 2-B is provided on the radiator module 2 for power supply operation, and the heat of each chip of the detector can be blown away by forced air cooling, realizing the third-stage refrigeration.

[0049] The present invention can adapt to different environments: When in a normal ventilation and room temperature environment (such as a laboratory), two-stage refrigeration is carried out using the internal TEC 5-A-4 and the multi-layer TEC 5-D of the device, and the fan is set to the sleep state, which can not only meet the heat dissipation requirements, but also avoid problems such as the short service life of the fan itself and the noise generated during operation; when in a harsh environment with poor wind speed and high ambient temperature (such as an equipment machine room), the fan 2-B is controlled to operate for third-stage refrigeration, and rapid heat exchange is achieved through forced air cooling.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A free-running single-photon detector with high integration, characterized in that: It includes a housing (1), a radiator module (2), a PCB board (3), a shielding cover module (4), and a secondary refrigeration module (5). The radiator module (2), the PCB board (3), the shielding cover module (4), and the secondary refrigeration module (5) are all enclosed within the housing (1). The PCB board (3) is fixed above the radiator module (2). The PCB board (3) is clamped in the middle of the shielding cover module (4). The bottom of the shielding cover module (4) is empty and is fixed on the upper surface of the radiator module (2). An opening is provided at the clamped part of the PCB board (3). The secondary refrigeration module (5) is placed at the middle opening of the PCB board (3) and its bottom surface contacts the heat dissipation surface on the radiator module (2).

2. The highly integrated free-running single-photon detector according to claim 1, wherein: The housing (1) is a square housing (1) jointly formed by a front panel (1 - A), a rear panel (1 - C), a ring frame (1 - B), and an upper cover (1 - D).

3. The highly integrated free-running single-photon detector according to claim 1, characterized in that: The PCB board (3) passes through the shielding cover module (4) and divides the shielding cover module (4) into upper and lower parts. The upper part of the circuit modules on the PCB board (3) is clamped in the middle of the shielding cover module (4).

4. The highly integrated free-running single-photon detector according to claim 1, wherein: The shielding cover module (4) is located at a corner of the radiator module (2). The upper end of the radiator module (2) extends out the mounting posts (202). The PCB board (3) is fixed on the mounting posts (202). There are 3 mounting posts (202). One corner of the PCB board (3) that is not fixed on the mounting posts (202) is supported and fixed by the shielding cover module (4).

5. The highly integrated free-running single-photon detector according to claim 4, characterized in that: The radiator module (2) also includes protruding stud structures (203). The protruding stud structures (203) contact the high - heat chips on the PCB board (3).

6. The highly integrated free-running single-photon detector according to claim 1, characterized in that: The radiator module (2) includes a radiator (2 - A) and a fan (2 - B). Multiple threaded holes (201) are provided on the side of the radiator (2 - A). Screws pass through the mounting holes of the fan (2 - B) and are fixed in the threaded holes (201) to achieve the installation of the fan (2 - B).

7. The highly integrated free-running single-photon detector according to claim 6, wherein: A cavity is provided at the position of the radiator (2 - A) corresponding to the installation of the fan (2 - B). The fan (2 - B) is entirely recessed into the radiator (2 - A) and integrated into one body.

8. The highly integrated free-running single-photon detector according to claim 1, wherein: The secondary refrigeration module (5) is enclosed within the enclosed space formed by the shielding cover module (4).

9. The highly integrated free-running single-photon detector according to claim 8, wherein: The material of the shielding cover module (4) is aluminum alloy. At the same time, the internal space of the shielding cover module (4) is filled with foam.

10. The highly integrated free-running single-photon detector according to claim 8, wherein: The secondary refrigeration module (5) includes an NFAD (5-A), a copper block base (5-B), a plastic pressing block (5-C), and multiple layers of TEC (5-D) arranged in sequence from top to bottom. The shape of the opening of the PCB board (3) matches the shape of the NFAD (5-A). The NFAD (5-A) is soldered to the PCB board (3). The NFAD (5-A) is located in the upper cavity of the shielding cover module (4). The copper block base (5-B), the plastic pressing block (5-C), and the multiple layers of TEC (5-D) are fixed together and located in the lower cavity of the shielding cover module (4). The NFAD (5-A) is fixed through the copper block base (5-B) located below the PCB board (3). Its optical fiber tail end passes through the optical fiber hole (406) provided at the bottom side of the shielding cover module (4). After fixing, the gap of the optical fiber hole (406) is filled with glue.

11. A highly integrated free-running single-photon detector according to claim 10, characterized in that: The bottom surface of the multiple layers of TEC (5-D) is in contact with the upper surface of the radiator (2-A). The plastic pressing block (5-C) is a ring frame, nested around the multiple layers of TEC (5-D), and at the same time has a groove structure at the bottom to press the bottom layer of the multiple layers of TEC (5-D). The plastic pressing block (5-C) is fixed on the surface of the radiator (2-A). The multiple layers of TEC (5-D) are fixedly installed between the radiator (2-A) and the plastic pressing block (5-C). The copper block base (5-B) is fixed on the plastic pressing block (5-C) and is in contact with the top surface of the multiple layers of TEC (5-D). The NFAD (5-A) is fixedly installed in the groove provided on the upper surface of the copper block base (5-B).

12. The highly integrated free-running single-photon detector according to claim 1, characterized in that: The shielding cover module (4) includes a shielding cover upper cover (4-A), a shielding cover (4-B), and a shielding cover ring frame (4-C). The bottom of the shielding cover module (4) is empty. The shielding cover upper cover (4-A) covers the shielding cover (4-B). The PCB board (3) is clamped between the shielding cover (4-B) and the shielding cover ring frame (4-C). The shielding cover upper cover (4-A) is fixed to the shielding cover (4-B). The PCB board (3) is fixed to the shielding cover (4-B) and the shielding cover ring frame (4-C). The shielding cover ring frame (4-C) is fixed to the upper surface of the radiator (2-A) through the bosses (405) around the bottom.

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