Back-side optically coupled superconducting nanowire single-photon detection device, preparation and testing device

Abstract

The present invention provides a back-light-coupled superconducting nanowire single-photon detection device, and a preparation and testing device. The back-light-coupled superconducting nanowire single-photon detection device includes a device photosensitive region and a positioning ring. The testing device includes a package and a sleeve. The back-light-coupled superconducting nanowire single-photon detection device is fixed in the package, and the sleeve is connected to the package and the optical fiber plug so that the center of the optical fiber plug and the center of the back-light-coupled superconducting nanowire single-photon detection device are located on the same vertical line. The present invention prepares a back-light-coupled superconducting nanowire single-photon detection device with a special morphology and uses it in conjunction with a testing device to achieve highly stable self-aligned optical coupling; and using a μm-level marking scale in combination with an optical microscope, the light alignment error can be directly quantified, so that the light alignment error is controlled at the μm level.

Description

Technical Field

[0001] The present invention belongs to the technical field of light detection, and relates to a back-light-coupled superconducting nanowire single-photon detection device, and a preparation and testing device. Background Art

[0002] Superconducting nanowire single photon detectors (SNSPDs) are a novel single-photon detection technology developed over the past decade. Their key advantages over semiconductor detectors are their ultra-high detection efficiency, fast response speed, and negligible dark counts, along with a spectral response range that spans the visible to infrared range. In 2001, Gol'tsman's group at Moscow Normal University successfully fabricated a 200nm-wide superconducting nanowire using a 5nm-thick NbN ultrathin film, achieving single-photon detection from the visible to the near-infrared range, thus establishing a precedent for SNSPDs. Since then, numerous countries and research groups in Europe, the United States, Russia, and Japan have conducted research on SNSPDs. After more than a decade of development, the detection efficiency of SNSPDs at a wavelength of 1.5μm has increased from less than 1% to over 70%, and even exceeded 90%, far exceeding the efficiency of semiconductor SPDs. In addition, its excellent performance in dark counting, low temporal jitter, and high count rate has been verified in many application fields. Therefore, the SNSPD with excellent performance near the near-infrared band undoubtedly provides an excellent tool for applications such as lidar and quantum information.

[0003] SNSPD has become a research hotspot in superconducting electronics and single-photon detection, and has significantly driven technological advancements in fields such as quantum information and lidar. Internationally renowned institutions involved in SNSPD research include MIT, JPL, and NIST in the United States, NICT in Japan, and MSPU in Russia. Currently, in the 1550nm optical fiber communication band, the device with the highest detection efficiency is developed by NIST in the United States using the ultra-low-temperature superconducting material WSi (operating temperature <1K), with a detection efficiency of 93%. An SNSPD developed using the low-temperature superconducting material NbN (operating temperature >2K) also achieves a maximum detection efficiency exceeding 80%. In addition to research institutions, there are currently six companies internationally specializing in SNSPD-related technology products.

[0004] With the development of SNSPD technology, its application range has expanded from the 1550nm band to other visible and near-infrared bands in recent years. This is partly due to the increasing demand for detectors in different bands, and partly due to the fact that multi-wavelength applications require detectors that can efficiently detect several different wavelengths simultaneously.

[0005] Existing single-photon detectors have two typical device structures: front-side optical coupling devices based on mirror structures (metal mirrors or dielectric high-reflection film structured mirrors) and back-side optical coupling devices based on optical cavities. The optical coupling methods are categorized into three main types: self-space optical coupling, fiber coupling, and waveguide coupling, depending on how light is transmitted to the photosensitive surface. Due to the limitation that the SNSPD operating environment must be below the temperature of liquid helium, the fiber-coupled SNSPD is currently the most widely used.

[0006] When SNSPD is coupled to an optical fiber, it mainly relies on mechanical adjustment to fix the package and uses optical methods to observe the light spot and the photosensitive surface. That is, the light spot emitted by the optical fiber is projected onto the photosensitive surface of the SNSPD. Under a microscope, the relative position of the optical fiber end face and the photosensitive surface of the SNSPD is adjusted, and then the position of the optical fiber and the SNSPD is mechanically fixed to perform optical coupling testing. However, existing back-side optically coupled superconducting nanowire single-photon detection devices cannot directly observe the photosensitive surface. Moreover, because GM refrigeration involves a certain frequency of mechanical movement during operation, the test device needs to undergo temperature increases and decreases from room temperature to the liquid helium temperature range. The thermal expansion and contraction of the test device material itself will cause the light spot emitted by the optical fiber to shift at low temperatures (usually on the order of μm).

[0007] Therefore, it is necessary to provide a back-side optically coupled superconducting nanowire single-photon detection device, a preparation and testing device to solve the disadvantage that the back-side optically coupled superconducting nanowire single-photon detection device cannot directly observe the photosensitive surface, improve the optical coupling alignment accuracy, reduce the random spot offset problem caused by temperature rise and fall in the optical coupling test, and realize high-stability self-aligned optical coupling. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a back-side optically coupled superconducting nanowire single-photon detection device, a preparation and testing device, which is used to solve the above-mentioned series of problems existing in the prior art when optically coupling back-side optically coupled superconducting nanowire single-photon detection devices.

[0009] To achieve the above-mentioned and other related objectives, the present invention provides a back-light-coupled superconducting nanowire single-photon detection device, the back-light-coupled superconducting nanowire single-photon detection device comprising:

[0010] Photosensitive area of ​​the device;

[0011] A positioning ring, wherein the positioning ring includes at least one positioning ring opening, the positioning ring passes through the superconducting nanowire single-photon detection device, and the positioning ring is located outside the photosensitive area of ​​the device.

[0012] Optionally, the center of the photosensitive area of ​​the device further includes a marking scale, and the light accuracy is quantified by the marking scale.

[0013] Optionally, the center of the positioning ring and the center of the photosensitive area of ​​the device are located on the same vertical line.

[0014] The present invention also provides a method for preparing a back-light-coupled superconducting nanowire single-photon detection device, comprising the following steps:

[0015] Providing a substrate, the substrate comprising a first surface and a second surface arranged corresponding to the first surface;

[0016] forming a superconducting nanowire on the first surface of the substrate;

[0017] forming a metal reflector optical cavity on the first surface of the substrate;

[0018] A photoresist is formed on the second surface of the substrate, the photoresist is patterned, and etching is performed using the patterned photoresist as a mask to form a positioning ring, wherein the positioning ring passes through the superconducting nanowire single-photon detection device, the positioning ring includes at least one positioning ring opening, and the positioning ring is located outside the photosensitive area of ​​the device.

[0019] Optionally, the center of the photosensitive area of ​​the device further includes a marking scale, which is formed at the same time as the superconducting nanowire is formed, and the marking scale is exposed in the optical cavity of the metal reflector, so that the light precision can be quantified by the marking scale.

[0020] The present invention also provides a testing device for testing the above-mentioned back-side optically coupled superconducting nanowire single-photon detection device, the testing device comprising:

[0021] A package, the package comprising a first component and a second component, the first component comprising a groove body, the groove body being arranged corresponding to the positioning ring, the second component comprising a through hole, the through hole exposing the photosensitive region of the device and the positioning ring, a receiving space for receiving the back-side light-coupled superconducting nanowire single-photon detection device being provided between the first component and the second component, and the receiving space being in communication with the groove body and the through hole;

[0022] The sleeve includes a first end and a corresponding second end. The first end of the sleeve is arranged corresponding to the groove body, and the first end of the sleeve is connected to the groove body through the through hole and the accommodating space, and the second end of the sleeve is connected to the optical fiber plug.

[0023] Optionally, the accommodating space is located in the first component, the second component includes a PCB circuit board, and the PCB circuit board is electrically connected to the back-side optically coupled superconducting nanowire single-photon detection device.

[0024] Optionally, the center of the optical fiber plug, the center of the sleeve, the center of the accommodating space and the center of the slot body are located on the same vertical line.

[0025] Optionally, the sleeve and the packaging component are made of ceramic or metal.

[0026] Optionally, the connection method between the first component and the second component includes one or a combination of clamping, pinning and threaded connection; the connection method between the sleeve and the optical fiber plug includes a tight fit, and the connection method between the sleeve and the slot body includes a tight fit.

[0027] As described above, the back-side light-coupled superconducting nanowire single-photon detection device, preparation and testing device of the present invention, by preparing a back-side light-coupled superconducting nanowire single-photon detection device with a special morphology and a testing device designed for testing the back-side light-coupled superconducting nanowire single-photon detection device, enables the back-side light-coupled superconducting nanowire single-photon detection device to be fixed in a package, and through the connection with the package and the optical fiber plug through the sleeve, the center of the optical fiber plug and the center of the back-side light-coupled superconducting nanowire single-photon detection device are located on the same vertical line, thereby realizing self-alignment of the optical fiber output light and the back-side light-coupled superconducting nanowire single-photon detection device; and by preparing a marking scale in the center of the photosensitive area of ​​the device, the light alignment accuracy can be quantified by the marking scale. The present invention solves the disadvantage of back-side optical coupling that the photosensitive surface cannot be directly observed during alignment. The test device uses a material with a low thermal expansion coefficient, and the sleeve is connected in a tight-fitting manner, thereby greatly reducing the random spot offset caused by heating and cooling during the optical coupling test, reducing systematic alignment errors, and achieving highly stable self-aligned optical coupling. Furthermore, the submicron-level high processing precision of micro-nano processing technology is utilized to process self-aligned devices with geometric dimensions at the μm level. A μm-level marking scale is used in combination with an optical microscope to directly quantify the alignment error, so that the alignment error is controlled at the μm level. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Shown is a schematic top view of the structure of the back-light-coupled superconducting nanowire single-photon detection device in the present invention.

[0029] Figure 2 Display as Figure 1 Schematic diagram of the cross-sectional structure of the back-side optically coupled superconducting nanowire single-photon detection device formed along the A-A' direction.

[0030] Figure 3 Shown is a schematic top view of the structure of a back-light-coupled superconducting nanowire single-photon detection device with a marked scale in the present invention.

[0031] Figure 4 Display as Figure 3Schematic diagram of the cross-sectional structure of the back-side optically coupled superconducting nanowire single-photon detection device formed along the BB' direction.

[0032] Figure 5 Shown is a process flow chart of the method for preparing a back-side optically coupled superconducting nanowire single-photon detection device in the present invention.

[0033] Figure 6 Shown is a schematic structural diagram of the testing device in the present invention.

[0034] Figure 7 Display as Figure 6 Schematic diagram of the cross-sectional structure formed along the C-C' direction.

[0035] Component number description

[0036] 100 Backside optically coupled superconducting nanowire single-photon detection device

[0037] 101 device photosensitive area

[0038] 102 locating ring

[0039] 10 Si substrate

[0040] 20 NbN superconducting nanowires

[0041] 30 SiO layers

[0042] 40 Metal Ag layer

[0043] 50 SiO2 lower anti-reflection layer

[0044] 60 SiO2 anti-reflection layer

[0045] 70 Marking Scale

[0046] 210 package

[0047] 211 First Part

[0048] 212 Second Part

[0049] 2121 Electrode

[0050] 220 casing

[0051] 300 fiber optic plug DETAILED DESCRIPTION

[0052] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0053] See also Figures 1 to 7 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0054] like Figure 1 This embodiment provides a back-light-coupled superconducting nanowire single-photon detection device 100, which includes: a device photosensitive region 101 and a positioning ring 102, wherein the positioning ring 102 includes at least one positioning ring opening, the positioning ring 102 passes through the back-light-coupled superconducting nanowire single-photon detection device 100, and the positioning ring 102 is located outside the device photosensitive region 101.

[0055] Specifically, the positioning ring opening serves as a connection portion for the back-side optically coupled superconducting nanowire single-photon detection device 100, connecting to the device's photosensitive region 101. The positioning ring 102, having a special morphology and extending through the back-side optically coupled superconducting nanowire single-photon detection device 100, cooperates with a sleeve 220 in a subsequent testing device. Through the testing device, the back-side optically coupled superconducting nanowire single-photon detection device 100 can be self-aligned, achieving highly stable self-aligned optical coupling. The specific implementation method will be described in detail later.

[0056] As an example, the center of the positioning ring 102 and the center of the device photosensitive area 101 are located on the same vertical line.

[0057] As an example, the shape of the positioning ring 102 can be set according to actual needs, and the shape of the positioning ring 102 can include a circular ring with the positioning ring opening, a square ring, etc. Preferably, in this embodiment, the shape of the positioning ring 102 is a circular ring to facilitate subsequent processing of the test device.

[0058] As an example, the back-side light-coupled superconducting nanowire single-photon detection device 100 includes a substrate, a superconducting nanowire and a metal reflector optical cavity. Furthermore, the upper surface of the substrate of the back-side light-coupled superconducting nanowire single-photon detection device 100 is also provided with an upper anti-reflection layer, and the lower surface of the substrate is also provided with a lower anti-reflection layer.

[0059] As an example, the substrate may include a Si substrate 10, an MgO substrate, or a sapphire substrate, and the specific thickness can be determined based on the preparation process selected. The thickness of the substrate can be set according to actual needs, for example, the thickness of the substrate can be, but is not limited to, 300 μm to 500 μm. Preferably, in this embodiment, the substrate is a commonly used Si substrate 10, and the thickness of the Si substrate 10 is selected to be 400 μm. Of course, other types of substrates or thicknesses may also be applicable to the present invention, and therefore, the present invention is not limited to the examples listed here.

[0060] As an example, the superconducting nanowire may include an NbN superconducting nanowire 20 , an Nb superconducting nanowire, a TaN superconducting nanowire, a MoSi superconducting nanowire, a MoGe superconducting nanowire, an NbTiN superconducting nanowire, or a WSi superconducting nanowire.

[0061] As an example, the superconducting nanowire may include a zigzag shape; the outline of the superconducting nanowire may include one or a combination of a circle, an ellipse and a polygon, which can be selected according to needs.

[0062] As an example, the width of the superconducting nanowire may be 50 nm to 100 nm, and the thickness of the superconducting nanowire may be 5 nm to 10 nm. The size and specific morphology of the superconducting nanowire may be set according to actual needs.

[0063] Specifically, in this embodiment, the superconducting nanowire uses the NbN superconducting nanowire 20, which has a thickness of 7 nm and a periodic zigzag shape, and each bend is a right angle or U-shaped corner, but the size and morphology of the NbN superconducting nanowire 20 are not limited thereto.

[0064] As an example, the metal mirror optical cavity may include a SiO layer 30 and a metal Ag layer 40 stacked in sequence, but is not limited to this. The SiO layer 30 may also be a SiO2 layer, and the metal Ag layer 40 may also be Au or Al. The upper anti-reflection layer may be a SiO2 upper anti-reflection layer 60, and the lower anti-reflection layer may be a SiO2 lower anti-reflection layer 50, but is not limited to this. SiO layer may also be used as the material of the upper anti-reflection layer or the lower anti-reflection layer.

[0065] As an example, the center of the photosensitive region 101 of the device further includes a marking scale 70 , through which the light precision is quantified.

[0066] Specifically, it is preferred that the marking scale 70 is formed at the same time as the NbN superconducting nanowire 20 is formed, but the present invention is not limited thereto. Figure 3 and Figure 4 The marking scale 70 is exposed in the optical cavity of the metal reflector, thereby quantifying the alignment accuracy. In this embodiment, the high submicron machining precision of micro-nanofabrication technology is utilized to produce a self-aligned device with geometric dimensions at the μm level. The μm-level marking scale 70, combined with an optical microscope, can directly quantify the alignment error, allowing the alignment error to be controlled at the μm level.

[0067] like Figure 5 This embodiment also provides a method for preparing a back-side optically coupled superconducting nanowire single-photon detection device, comprising the following steps:

[0068] Providing a substrate, the substrate comprising a first surface and a second surface arranged corresponding to the first surface;

[0069] forming a superconducting nanowire on the first surface of the substrate;

[0070] forming a metal reflector optical cavity on the first surface of the substrate;

[0071] A photoresist is formed on the second surface of the substrate, the photoresist is patterned, and etching is performed using the patterned photoresist as a mask to form a positioning ring, wherein the positioning ring passes through the superconducting nanowire single-photon detection device, the positioning ring includes at least one positioning ring opening, and the positioning ring is located outside the photosensitive area of ​​the device.

[0072] As an example, when the center of the photosensitive area of ​​the device also includes a marking scale, it is preferred that the marking scale is formed while forming the superconducting nanowire, and the marking scale is exposed in the optical cavity of the metal mirror to quantify the light accuracy through the marking scale.

[0073] Specifically, the structure and material selection of the back-light-coupled superconducting nanowire single-photon detection device can be found in the aforementioned back-light-coupled superconducting nanowire single-photon detection device 100 and will not be further described here. The superconducting nanowires can be formed using an EBL process, the metal reflector optical cavity can be formed using electron beam evaporation to deposit the SiO layer 30 and the metal Ag layer 40, and the positioning ring can be formed using an ICP etching process. The marking scale is formed simultaneously with the superconducting nanowires, further improving the positional accuracy of the marking scale.

[0074] like Figures 6 and 7 This embodiment further provides a testing device for testing the back-side optically coupled superconducting nanowire single-photon detection device 100. The testing device includes: a package 210, wherein the package 210 includes a first component 211 and a second component 212. The first component 211 includes a groove, which is correspondingly arranged with the positioning ring 102. The second component 212 includes a through hole, which exposes the device photosensitive region 101 and the positioning ring 102. A receiving space for receiving the back-side optically coupled superconducting nanowire single-photon detection device 100 is provided between the first component 211 and the second component 212, and the receiving space is connected to the groove and the through hole.

[0075] The sleeve 220 includes a first end and a corresponding second end. The first end of the sleeve 220 is arranged corresponding to the groove body, and the first end of the sleeve 220 is connected to the groove body through the through hole and the accommodating space. The second end of the sleeve 220 is connected to the optical fiber plug 300.

[0076] As an example, the trough body and the positioning ring 102 of the back-side optically coupled superconducting nanowire single-photon detection device 100 preferably have the same morphology and can overlap in the vertical direction, so as to facilitate the trough body's support of the back-side optically coupled superconducting nanowire single-photon detection device 100. The first end of the sleeve 220 preferably has the same morphology as the positioning ring 102 of the back-side optically coupled superconducting nanowire single-photon detection device 100 and can overlap in the vertical direction, so as to facilitate the connection of the sleeve 220 to the trough body and the back-side optically coupled superconducting nanowire single-photon detection device 100.

[0077] As an example, the accommodating space may be located in the first component 211, or in the second component 212, or formed by a combination of the first component 211 and the second component 212. The specific selection may be made based on the materials of the first component 211 and the second component 212 for ease of processing and preparation.

[0078] As an example, the second component 212 includes a PCB circuit board, and the PCB circuit board is electrically connected to the back-side optically coupled superconducting nanowire single-photon detection device 100, so as to simplify the structure of the test equipment and facilitate subsequent optical coupling testing of the back-side optically coupled superconducting nanowire single-photon detection device 100, but the present invention is not limited to this. In this embodiment, it is preferred that the second component 212 uses the PCB circuit board and the PCB circuit board is provided with an electrode 2121, the accommodation space is located within the first component 211, and the back-side optically coupled superconducting nanowire single-photon detection device 100 partially exposes the accommodation space, so as to facilitate electrical connection between the back-side optically coupled superconducting nanowire single-photon detection device 100 and the electrode 2121, but the electrical connection method of the back-side optically coupled superconducting nanowire single-photon detection device 100 is not limited to this, and other connection methods may also be used, and no excessive restrictions are imposed here.

[0079] As an example, the center of the optical fiber plug 300 , the center of the sleeve 220 , the center of the accommodating space, and the center of the slot are located on the same vertical line, so as to further improve the accuracy of the self-aligned optical coupling.

[0080] As an example, the sleeve 220 and the package 210 are preferably made of a material with a low thermal expansion coefficient, such as ceramic, metal, etc., so as to reduce the problem of the optical fiber output light spot being offset at low temperatures due to the thermal expansion and contraction of the test device material itself caused by the temperature increase or decrease during optical coupling, thereby improving the optical coupling alignment accuracy and achieving highly stable self-aligned optical coupling.

[0081] As an example, the connection method between the first component 211 and the second component 212 includes one or a combination of clamping, pinning and threaded connection.

[0082] As an example, the connection method between the sleeve 220 and the optical fiber plug 300 includes a tight fit, and the connection method between the sleeve 220 and the slot body includes a tight fit, thereby reducing the random spot deviation caused by the optical fiber plug 300, the sleeve 220 and the slot body during heating and cooling.

[0083] Specifically, such as Figure 6 and Figure 7In this embodiment, the accommodation space for accommodating the back-light-coupled single-photon detection device 100 is located in the first component 211, and the back-light-coupled single-photon detection device 100 partially exposes the accommodation space. The second component 212 adopts the PCB circuit board, and the PCB circuit board is provided with an electrode 2121, so as to be directly electrically connected to the back-light-coupled single-photon detection device 100 that exposes the accommodation space through the electrode 2121; the groove body and the positioning ring 102 have the same morphology and can overlap on the vertical line, so as to support the back-light-coupled single-photon detection device 100 and facilitate the groove body. and the back-side optically coupled single-photon detection device 100 is tightly fitted with the sleeve 220; the groove body passes through the first component 211 to further improve the tight fit between the groove body and the sleeve 220; preferably, the edge of the through hole provided on the PCB circuit board coincides with the edge of the positioning ring 102 on the vertical line, so as to facilitate the tight fit between the sleeve 220 and the PCB circuit board while avoiding blocking the outgoing light of the optical fiber plug 300; the connection method between the optical fiber plug 300 and the sleeve 220 is preferably tight fit; thereby, the sleeve 220 is connected in a tight fit manner to achieve highly stable self-aligned optical coupling.

[0084] In summary, the back-side light-coupled superconducting nanowire single-photon detection device, preparation and testing device of the present invention, by preparing a back-side light-coupled superconducting nanowire single-photon detection device with a special morphology and a testing device designed for testing the back-side light-coupled superconducting nanowire single-photon detection device, enables the back-side light-coupled superconducting nanowire single-photon detection device to be fixed in a package, and through the connection with the package and the optical fiber plug through a sleeve, the center of the optical fiber plug and the center of the back-side light-coupled superconducting nanowire single-photon detection device are located on the same vertical line, thereby realizing self-alignment of the optical fiber output light and the back-side light-coupled superconducting nanowire single-photon detection device; and by preparing a marking scale in the center of the photosensitive area of ​​the device, the light alignment accuracy can be quantified by the marking scale. The present invention addresses the drawback of back-side optical coupling, which prevents direct observation of the photosensitive surface during alignment. The test device utilizes a material with a low thermal expansion coefficient, and the sleeve is connected in a tight-fitting manner. This significantly reduces the random spot offset caused by temperature fluctuations during optical coupling testing, reduces systematic alignment errors, and achieves highly stable self-aligned optical coupling. Furthermore, the submicron-level high processing precision of micro-nanofabrication technology is utilized to produce self-aligned devices with micron-level geometric dimensions. A micron-level marking scale, combined with an optical microscope, allows for direct quantification of alignment errors, enabling control of alignment errors to the micron level. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and possesses high industrial value.

[0085] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A back-light-coupled superconducting nanowire single-photon detection device, characterized in that: The back-side optically coupled superconducting nanowire single-photon detection device comprises: Photosensitive area of ​​the device; A positioning ring, the positioning ring comprising at least one positioning ring opening, the positioning ring passing through the back-light-coupled superconducting nanowire single-photon detection device, and the positioning ring being located at the periphery of the photosensitive region of the device; The center of the photosensitive area of ​​the device includes a marking scale, and the light precision is quantified by the marking scale; The center of the positioning ring and the center of the photosensitive area of ​​the device are located on the same vertical line; The method for preparing the back-side optically coupled superconducting nanowire single-photon detection device comprises the following steps: Providing a substrate, the substrate comprising a first surface and a second surface arranged corresponding to the first surface; forming a superconducting nanowire on the first surface of the substrate; forming a metal reflector optical cavity on the first surface of the substrate; forming a photoresist on the second surface of the substrate, patterning the photoresist, and performing etching using the patterned photoresist as a mask to form a positioning ring; The marking scale is formed while the superconducting nanowire is formed, and the marking scale is exposed in the optical cavity of the metal reflector, so that the light alignment accuracy can be quantified by the marking scale.

2. A testing device for testing the back-light-coupled superconducting nanowire single-photon detection device according to claim 1, characterized in that: The testing device comprises: A package, the package comprising a first component and a second component, the first component comprising a groove body, the groove body being arranged corresponding to the positioning ring, the second component comprising a through hole, the through hole exposing the photosensitive region of the device and the positioning ring, a receiving space for receiving the back-side light-coupled superconducting nanowire single-photon detection device being provided between the first component and the second component, and the receiving space being in communication with the groove body and the through hole; a sleeve, the sleeve comprising a first end and a corresponding second end, the first end of the sleeve being disposed corresponding to the slot body, and the first end of the sleeve being connected to the slot body via the through hole and the accommodating space, and the second end of the sleeve being connected to the optical fiber plug; The center of the optical fiber plug, the center of the sleeve, the center of the accommodating space and the center of the slot body are located on the same vertical line.

3. The testing device for testing the back-side optically coupled superconducting nanowire single-photon detection device according to claim 1 according to claim 2, characterized in that: The accommodating space is located in the first component, the second component includes a PCB circuit board, and the PCB circuit board is electrically connected to the back-side optically coupled superconducting nanowire single-photon detection device.

4. The testing device for testing the back-side optically coupled superconducting nanowire single-photon detection device according to claim 1 according to claim 2, characterized in that: The sleeve and the packaging component are made of ceramic or metal.

5. The testing device for testing the back-side optically coupled superconducting nanowire single-photon detection device according to claim 1 according to claim 2, characterized in that: The connection method between the first component and the second component includes one or a combination of clamping, pinning and threaded connection; the connection method between the sleeve and the optical fiber plug includes tight fit, and the connection method between the sleeve and the slot body includes tight fit.

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