Superconducting nanowire single photon detection device and method

Abstract

The invention discloses a superconducting nanowire single-photon detection device and method, and belongs to the field of single-photon detection. The device comprises a four-quadrant superconducting nanowire single photon array detection module, a low-temperature system, a data acquisition and test module and an orientation detection processing module. The method comprises the following steps: receiving a diffuse reflection echo optical signal of a detected target and converting the diffuse reflection echo optical signal into a pulse electric signal with amplitude difference; amplifying the pulse electric signal to a recognizable level, and sending out an output signal; counting amplitude counting distribution of the output signal; and based on the statistical amplitude counting distribution, calculating a light spot position through a pulse amplitude mapping matrix, and outputting sub-pixel-level deflection angle information. The device and the method disclosed by the invention have single photon sensitivity and nanosecond-level response, realize sub-pixel-level positioning, high-precision tracking and high-sensitivity detection of a long-distance dynamic target, and are suitable for the fields of long-distance detection, dynamic target investigation and the like.

Description

Technical Field

[0001] The present invention belongs to the field of single - photon detection, and is applicable to high - precision positioning of long - distance dynamic targets. More specifically, it relates to a superconducting nanowire single - photon detection device and method. Background Art

[0002] Traditional quadrant detectors (such as PIN, APD) rely on the difference in photocurrent to calculate the position of the light spot, but have the following limitations: (1) Low sensitivity: When detecting at a long distance, the energy of the target echo is very low, and the responsivity of ordinary quadrant detectors is too low to detect signals at the single - photon energy level. (2) Narrow dynamic range: It is easy to saturate under strong signals, and the signal - to - noise ratio is insufficient under weak light. Limited by thermal noise and dark current, it cannot meet the detection requirements of long - and short - distance dynamic targets. (3) Slow response speed: Traditional quadrant detectors have a response delay of microseconds and cannot meet the requirements of high - speed dynamic tracking. (4) Limited resolution: When the light spot completely falls into a single quadrant, the specific position of the light spot within the quadrant cannot be further located, resulting in difficulty in sub - pixel - level light - spot positioning.

[0003] Existing detection and positioning systems usually adopt single - point detection or simple quadrant arrays, and cannot achieve high - precision azimuth calculation and dynamic - range expansion. Summary of the Invention

[0004] In order to solve the problems of low sensitivity, narrow dynamic range, and insufficient positioning accuracy existing in detectors during long - distance detection in the prior art, the present invention discloses a superconducting nanowire single - photon detection device and method to achieve sub - pixel - level positioning, high - precision tracking, and high - sensitivity detection of long - distance dynamic targets.

[0005] According to the first aspect of the present invention, a superconducting nanowire single - photon detection device is provided, comprising: a quadrant superconducting nanowire single - photon array detection module for receiving the diffuse - reflection return light signal of the target to be detected and converting it into pulse electrical signals with amplitude differences.

[0006] A cryogenic system for providing a temperature less than or equal to a preset value and a vacuum environment for the quadrant superconducting nanowire single - photon array detection module to make it in a superconducting state.

[0007] A circuit module for reading out and amplifying the pulse electrical signals to an identifiable level and outputting them to a data acquisition and test module.

[0008] A data acquisition and test module for counting the amplitude count distribution based on the pulse electrical signals.

[0009] An azimuth detection and processing module for calculating the position of the light spot through a pulse - amplitude mapping matrix based on the counted amplitude count distribution and outputting deflection angle information.

[0010] A superconducting nanowire single - photon orientation device according to an embodiment of the present disclosure includes: an optical system for emitting pulsed laser light towards the target to be detected, receiving the diffuse - reflected back - light signal of the target to be detected, and transmitting the diffuse - reflected back - light signal to the quadrant superconducting nanowire single - photon array detection module.

[0011] According to an embodiment of the present disclosure, the quadrant superconducting nanowire single - photon array detection module includes a 16 - pixel superconducting nanowire array. Each quadrant includes 4 pixels. The nanowire array adopts a polarization - insensitive orthogonal design, and different - value resistors are connected in parallel to each pixel.

[0012] According to an embodiment of the present disclosure, the power supply module includes a bias circuit formed by a constant - voltage source and a current - limiting resistor in series, and is used to provide a bias current for the quadrant superconducting nanowire single - photon array detection module.

[0013] According to an embodiment of the present disclosure, the circuit module includes a read - out circuit module. The read - out circuit module includes Bias - Tee circuits coupled to each quadrant; the Bias - Tee circuit includes a coupling capacitor C, a parallel - connected inductor L s and a shunt resistor R s . The read - out circuit module is used to read out the pulsed electrical signal.

[0014] According to an embodiment of the present disclosure, the read - out circuit module adopts a symmetric cryogenic PCB design, and the four - way detector units reduce crosstalk through a star layout. According to an embodiment of the present disclosure, the circuit module includes a power supply module; the power supply module includes a bias circuit formed by a constant - voltage source and a current - limiting resistor in series, and is used to provide a bias current for the quadrant superconducting nanowire single - photon array detection module. According to an embodiment of the present disclosure, the optical system includes a pulsed laser for emitting pulsed laser light. The pulsed laser light is directed towards the target to be detected through a polarization controller, an adjustable optical attenuator, and a beam expander; the diffuse - reflected back - light signal of the target to be detected can be transmitted to the quadrant superconducting nanowire single - photon array detection module through a telescope, a filter, and an echo mirror.

[0015] According to an embodiment of the present disclosure, the optical system includes a beam splitter and a flip - mirror; part of the pulsed laser light can be reflected after passing through the beam splitter and is directed towards the echo mirror through the flip - mirror for collimating the optical path.

[0016] According to an embodiment of the present disclosure, the cryogenic system includes a vacuum chamber, a vacuum chamber window, a filter set, and a focusing lens provided in the vacuum chamber; the quadrant superconducting nanowire single photon array detection module is placed inside the vacuum chamber; the diffuse reflection return optical signal of the detected target is received by the quadrant superconducting nanowire single photon array detection module through the vacuum chamber window, the filter set, and the focusing lens.

[0017] Another aspect of the embodiments of the present disclosure provides a superconducting nanowire single photon detection method, which is applied to a superconducting nanowire single photon detection device. The method includes: receiving the diffuse reflection return optical signal of the detected target and converting it into a pulsed electrical signal with amplitude differences; amplifying the pulsed electrical signal to an identifiable level and emitting an output signal; statistically analyzing the amplitude count distribution of the output signal; and calculating the spot position through a pulse amplitude mapping matrix based on the statistically analyzed amplitude count distribution, and outputting deflection angle information.

[0018] According to an embodiment of the present disclosure, calculating the spot position through a pulse amplitude mapping matrix based on the statistically analyzed amplitude count distribution includes: calculating the first offsets of the centroid of the target spot on the x-axis and y-axis according to the quadrant pulse counts of the amplitude count distribution by the sum-difference method:

[0019] According to an embodiment of the present disclosure, calculating the spot position through a pulse amplitude mapping matrix and outputting deflection angle information includes: decoupling the click situation of each quadrant according to the amplitude count distribution, reconstructing the pulse statistical counts of the pixels in each quadrant, and constructing a pixel-level amplitude mapping matrix; calculating the second offset of the spot according to the amplitude mapping matrix; calculating the global coordinate offset of the spot position according to the first offset and the second offset; calculating the azimuth angle according to the global coordinate offset; and outputting sub-pixel level deflection angle information.

[0020] Advantageous effects:

[0021] One or more of the above embodiments have the following advantageous effects:

[0022] 1. Achieved sub-pixel level positioning, high-precision tracking, and high-sensitivity detection of a long-distance dynamic target

[0023] The superconducting nanowire single photon detection device disclosed in the present invention includes a quadrant superconducting nanowire single photon array detection module, a cryogenic system, a data acquisition and test module, and an azimuth detection and processing module. By receiving the diffuse reflection return optical signal of the detected target and converting it into a pulsed electrical signal with amplitude differences, calculating the initial azimuth angle based on the statistically analyzed amplitude count distribution, correcting the spot position through a pulse amplitude mapping matrix, and outputting sub-pixel level deflection angle information, sub-pixel level positioning, high-precision tracking, and high-sensitivity detection of a long-distance dynamic target are achieved.

[0024] 2. Improve the long-distance detection performance at the single-photon level

[0025] The superconducting nanowire single-photon detection device disclosed in the present invention utilizes the single-photon detection ability of the quadrant superconducting nanowire array, can efficiently capture the weak echo signals of distant dynamic detected targets, realizes the improvement of the detection range, breaks through the sensitivity limit of traditional detectors, and significantly improves the long-distance detection performance.

[0026] 3. Expand the dynamic range to meet the wide-range detection requirements

[0027] The superconducting nanowire single-photon detection device disclosed in the present invention, through the low-temperature amplification circuit module and adopting adaptive threshold adjustment, can amplify strong and weak signals without distortion, increase the detection dynamic range, meet the wide-range detection requirements, and ensure the stable tracking of targets at different distances.

[0028] 4. Anti-interference design to ensure stability in complex environments

[0029] The superconducting nanowire single-photon detection device disclosed in the present invention effectively suppresses background noise through the low-temperature system and the filter stack, and cooperates with the symmetric readout circuit module to reduce crosstalk, can significantly improve the signal-to-noise ratio, ensure the signal stability in complex environments, and significantly enhance the robustness of the device in strong interference scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Through the following description of the embodiments of the present disclosure with reference to the drawings, the above content and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0031] Figure 1 Schematically shows an application scenario diagram of the superconducting nanowire single-photon detection device and method according to an embodiment of the present disclosure.

[0032] Figure 2 Schematically shows a block diagram of a superconducting nanowire single-photon directional device according to an embodiment of the present disclosure.

[0033] Figure 3 Schematically shows a structural schematic diagram of a superconducting nanowire single-photon directional device according to an embodiment of the present disclosure.

[0034] Figure 4 Schematically shows a design diagram of a quadrant superconducting nanowire single-photon array detection module according to an embodiment of the present disclosure.

[0035] Figure 5 Schematically shows a connection diagram of a readout circuit module according to an embodiment of the present disclosure.

[0036] Figure 6Schematically shown are 15 output pulse signal diagrams that can be collected by the data acquisition and testing module according to an embodiment of the present disclosure, as well as a schematic diagram of the determination example of the number of photons and position resolution for any output situation according to the amplitude mapping matrix.

[0037] Figure 7 Schematically shown is a flowchart of a superconducting nanowire single-photon detection method according to an embodiment of the present disclosure.

[0038] Figure 8 Schematically shown is a schematic diagram of a method for resolving target azimuth information according to an embodiment of the present disclosure.

[0039] The reference numerals involved in the above-mentioned drawings are as follows:

[0040] 100. Detection device;

[0041] 1. Optical system, 101. Pulse laser, 102. Polarization controller, 103. Beam splitter, 104. Adjustable optical attenuator, 105. First three-axis mirror, 106. Second three-axis mirror, 107. Beam expander, 108. Target to be detected (distant dynamic target), 109. Telescope, 110. First filter, 111. Flip mirror, 112. Third three-axis mirror, 113. Fourth mirror, 114. Six-axis displacement stage;

[0042] 2. Cryogenic system, 201. Vacuum chamber window, 202. Vacuum feedthrough, 215 Second filter, 216 Third filter, 217 Fourth filter, 218 Focusing lens;

[0043] 3. Quadrant superconducting nanowire single-photon array detection module, 301. Peripheral electrode region, 302. Nanowire region, 303. Ti / Au double-layer contact pads, 304. Ti resistance region, QD-1. First quadrant, QD-2. Second quadrant, QD-3. Third quadrant, QD-4. Fourth quadrant;

[0044] 4. Circuit module, 401. Power supply module, 402. Readout circuit module, 403. Cryogenic amplifier circuit module;

[0045] 5. Data acquisition and testing module;

[0046] 6. Azimuth detection and processing module.

[0047] It should be noted that, for clarity, in the drawings used to describe the embodiments of the present disclosure, the dimensions of the overall / local structure or the overall / local region may be enlarged or reduced, that is, these drawings are not drawn according to the actual scale. Detailed implementation manners

[0048] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure. However, it is obvious that one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present disclosure.

[0049] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0050] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0051] Superconducting nanowire single photon detectors (SNSPDs) have good single photon sensitivity, nanosecond response speed, and low dark count rate, making them an ideal choice for long-distance detection. However, existing SNSPD-based positioning systems usually cannot achieve high-precision azimuth resolution and dynamic range expansion.

[0052] To solve the problems of low sensitivity, narrow dynamic range, and insufficient positioning accuracy of detectors in long-distance detection in the prior art, embodiments of the present disclosure provide a superconducting nanowire single photon detection device, comprising: a quadrant superconducting nanowire single photon array detection module for receiving the diffuse reflection return optical signal of the detected target and converting it into a pulsed electrical signal with amplitude differences; a cryogenic system for providing a cryogenic temperature and vacuum environment less than or equal to a preset value for the quadrant superconducting nanowire single photon array detection module to make it in a superconducting state; a circuit module for reading out and amplifying the pulsed electrical signal to an identifiable level and outputting it to a data acquisition and test module; a data acquisition and test module for counting the amplitude count distribution based on the pulsed electrical signal; and an azimuth detection and processing module for calculating the spot position through a pulse amplitude mapping matrix based on the counted amplitude count distribution and outputting the deflection angle information.

[0053] Figure 1 Schematically shows an application scenario diagram of the superconducting nanowire single photon detection device according to an embodiment of the present disclosure. It should be noted that Figure 1The illustration below is only an example where the embodiments of the present disclosure can be applied, to help those skilled in the art understand the technical content of the present disclosure. However, it does not mean that the embodiments of the present disclosure cannot be used in other devices, systems, environments or scenarios.

[0054] As Figure 1 shown, the application scenario according to this embodiment may include a detection device 100 and a long-distance dynamic target 108. The scenario of this embodiment is generally a situation where, at a relatively long distance, the detection device 100 is used to detect, identify, and track a target in a moving state. Specifically, in a vast natural environment, such as the ocean, forest, desert, etc., or in a complex urban environment, various detection devices (such as detection devices including radar, optical cameras, infrared detection functions, etc. The devices and methods of the embodiments of the present disclosure may be functional parts of the above various detection devices) are used to obtain information of dynamic targets from a long distance. For example, a radar system on the coastline monitors ships sailing in the far sea; cameras in border areas track moving people and vehicles; infrared detectors in forest fire prevention areas detect moving fire sources or animals. Detectable objects include transportation means (such as: airplanes, drones, ships, cars, trains, etc.), personnel (such as: pedestrians on foot, outdoor activity personnel, illegal border-crossing personnel, etc.), animals (such as large wild animals, such as elephants, tigers, etc., for monitoring their activities in nature reserves), and other dynamic targets (such as: moving fire sources, floating objects, space targets, etc.). The detection device 100 can detect a variety of target types and is used in a variety of application scenarios.

[0055] The detection device 100 can integrate one or more detection functions. In terms of design, the detection device 100 can be integrally designed or separately designed. For example: the signal transmission part and the signal sensing and analysis part can be separately designed, and the echo signal of the detected target is transmitted to the signal sensing and analysis part through corresponding interfaces for analysis; the signal sensing and analysis part can also be separately designed. For example, some signal analysis and calculation functions can be implemented by a computer, but each part cooperates with each other to achieve the function of signal sensing and analysis as a whole.

[0056] The analysis results of the detection device 100 can be further used for monitoring, management, alarm, etc. of the detected target, and thus can be used in a variety of specific scenarios such as transportation, border management, urban governance, and environmental protection.

[0057] The following will be based on Figure 1 the described scenario, in combination with Figures 2 - 6 to describe in detail. A detailed description of the superconducting nanowire single-photon detection device of the embodiments of the present disclosure will be given.

[0058] Figure 2A structural block diagram of a superconducting nanowire single-photon detection device according to an embodiment of the present disclosure is schematically shown. As shown in the figure, the superconducting nanowire single-photon detection device of this embodiment includes:

[0059] A quadrant superconducting nanowire single-photon array detection module 3, configured to receive the diffuse reflected light signal of the target to be detected and convert it into a pulsed electrical signal with amplitude differences.

[0060] A cryogenic system 2, configured to provide a temperature less than or equal to a preset value and a vacuum environment for the quadrant superconducting nanowire single-photon array detection module 3, so that it is in a superconducting state.

[0061] A circuit module 4, configured to read out and amplify the pulsed electrical signal to an identifiable level and output it to a data acquisition and test module 5.

[0062] A data acquisition and test module 5, configured to receive the pulsed electrical signal and statistically analyze the amplitude count distribution.

[0063] An azimuth detection and processing module 6, configured to calculate the spot position based on the statistically analyzed amplitude count distribution through a pulsed amplitude mapping matrix and output sub-pixel level deflection angle information.

[0064] In an embodiment of the present disclosure, the superconducting nanowire single-photon orientation device further includes: an optical system 1, configured to emit pulsed laser light to the target to be detected, receive the diffuse reflected light signal of the target to be detected, and transmit the diffuse reflected light signal to the quadrant superconducting nanowire single-photon array detection module 3.

[0065] In an embodiment of the present disclosure, the optical system includes a pulsed laser, configured to emit pulsed laser light that is directed to the target to be detected through a polarization controller, an adjustable optical attenuator, and a beam expander; the diffuse reflected light signal of the target to be detected can be transmitted to the quadrant superconducting nanowire single-photon array detection module through a telescope, a filter, and a retroreflector.

[0066] In an embodiment of the present disclosure, the polarization controller, the adjustable optical attenuator, and the beam expander are arranged in the optical system. The pulsed laser emits pulsed laser light, and after the polarization state is adjusted by the polarization controller, the attenuation multiple is dynamically adjusted by the adjustable optical attenuator, and then the beam diameter is expanded by the beam expander and directed to a long-distance dynamic target to be detected.

[0067] In an embodiment of the present disclosure, the optical system includes a beam splitter and a flip mirror. The pulsed laser can be partially reflected by the beam splitter and is directed towards the echo mirror through the flip mirror to collimate the optical path. In this embodiment, the beam splitter can divide the pulsed laser into two paths: reflected light and transmitted light. The reflected light is used to collimate the optical path and is output after the direction is adjusted by the flip mirror. The transmitted light is dynamically adjusted in attenuation multiple by the adjustable optical attenuator, and the beam diameter is expanded by the beam expander and then directed towards the target to be detected.

[0068] In an embodiment of the present disclosure, in the optical path for emitting the pulsed laser towards the target to be detected, a plurality of three-axis mirrors can be provided for adjusting the optical path. For example, two opposite three-axis mirrors can be provided between the adjustable optical attenuator and the beam expander. After the pulsed laser is dynamically adjusted in attenuation multiple by the adjustable optical attenuator, it is directed into the beam expander after the direction is adjusted by the two three-axis mirrors.

[0069] As Figure 3 shown in the embodiment, the optical system 1 includes a pulsed laser 101, a polarization controller 102, a beam splitter 103, an adjustable optical attenuator 104, a first three-axis mirror 105, a second three-axis mirror 106, a beam expander 107, a telescope 109, a first filter 110, a flip mirror 111, a third three-axis mirror 112 (echo mirror), a fourth mirror 113, and a six-axis displacement stage 114.

[0070] The working process of the optical path system is as follows:

[0071] 1. Pulsed laser emission and adjustment: The pulsed laser 101 emits a pulsed laser. After the polarization state is adjusted by the polarization controller 102, it is divided into two paths: reflected light and transmitted light by the 50:50 beam splitter 103. The reflected light is used to collimate the optical path and is output after the direction is adjusted by the flip mirror 111. The transmitted light is dynamically adjusted in attenuation multiple by the adjustable optical attenuator 104, the optical path direction is adjusted by the first three-axis mirror 105 and the second three-axis mirror 106, and then the beam diameter is expanded by the beam expander 107 and directed towards the target to be detected 108.

[0072] 2. Echo reception and processing: The diffuse reflection echo of the target to be detected is received by the telescope 109, and the stray light and noise in non-signal wavelength bands are filtered out by the first filter 110. The filtered optical signal passes through the third three-axis mirror 112 and the fourth mirror 113 located on the six-axis displacement stage 114 in sequence. After the direction is precisely calibrated, it passes through the vacuum chamber window 201 of the cryogenic system.

[0073] Among them, the flip mirror 111 participates in the collimation optical path during the laser emission stage; it flips to the non-working state during the echo reception stage to ensure that the signal optical path received from the telescope 109 is unobstructed. The six-axis displacement stage 114 realizes the precise alignment and dynamic tracking of the light spot by finely adjusting the angle and position of the fourth mirror 113.

[0074] In this embodiment, the optical system 1 uses a pulsed laser 101 to emit laser light, and realizes optical path collimation and energy adjustment through components such as a polarization controller 102, a beam splitter 103, an adjustable optical attenuator 104, and a beam expander 107. The optical system 1 ensures the strict collimation of the optical path and the efficient coupling of the signal light through the coordinated control of multiple mirrors (the first three-axis mirror 105, the second three-axis mirror 106, the third three-axis mirror 112, and the fourth mirror 113) and the six-axis displacement stage (114), and realizes the real-time tracking and high-precision positioning of a distant dynamic target 108 to be detected. The optical system 1 receives the diffuse reflection echo of the target 108 to be detected through a telescope 109 and a filter set, and accurately calibrates the optical path through the fourth mirror 113 with a six-axis displacement stage 114 to ensure that the signal light is efficiently coupled to the four-quadrant superconducting nanowire single-photon array detection module 3.

[0075] As Figure 3 shown, in an embodiment of the present disclosure, the cryogenic system includes a vacuum chamber window 201, a vacuum feedthrough 202, and a vacuum chamber and a shielding cover. The components work together as follows: The vacuum chamber window 201 is made of 5 mm thick BK7 (borosilicate glass) material, which is used to realize free-space optical coupling to ensure that the signal light efficiently enters the vacuum chamber. The vacuum feedthrough 202 is mainly a coaxial feedthrough, which is responsible for transmitting electrical signals in and out of the vacuum chamber to ensure the stable transmission of signals. The vacuum chamber is used to construct a vacuum-tight environment and maintain a low temperature of 0.8K inside. In this embodiment, it can be in a vacuum environment of -0.1 MPa. The shielding cover is used to provide thermal shielding to reduce the influence of the external environment on the cryogenic system and ensure the stable operation of the detector and the cryogenic amplifier.

[0076] In this embodiment, the cryogenic system 2 realizes optical coupling through the vacuum chamber window 201, transmits signals using the vacuum feedthrough 202, combines the vacuum chamber and the shielding cover to maintain a low-temperature environment, provides a 0.8K working environment for the four-quadrant superconducting nanowire single-photon array detector, and provides a 4K environment for the cryogenic amplifier to ensure the high sensitivity and stability of the device. In this embodiment, temperature environments of 300K, 40K, 4K, and 0.8K are gradually realized through designs such as the vacuum chamber and the shielding cover.

[0077] The filter set of the cryogenic system 2 in this embodiment includes a second filter 215, a third filter 216, and a fourth filter 217, which are used to filter room-temperature blackbody radiation. The diffuse-reflected return optical signal of the detected target 108 passes through the fourth reflector 113, the second filter 215, the third filter 216, and the fourth filter 217, and finally the signal light is focused by the transmission focusing lens 218 onto the photosensitive area of the quadrant superconducting nanowire single-photon array detection module, completing the input of the signal spot.

[0078] In an embodiment of the present disclosure, the quadrant superconducting nanowire single-photon array detection module includes a 16-pixel superconducting nanowire array, with each quadrant containing 4 pixels. The nanowire array adopts a polarization-insensitive orthogonal design, and different-valued resistors are connected in parallel to each pixel. In this embodiment, the 16-pixel superconducting nanowire array is specifically a MoSi superconducting nanowire array.

[0079] As Figure 3 shown, in this embodiment, the quadrant superconducting nanowire array includes a peripheral electrode region 301, a nanowire region 302, Ti / Au bilayer contacts 303, and a Ti resistor region 304. The quadrant superconducting nanowire array is arranged in a 0.8K cryogenic environment provided by the cryogenic system 2.

[0080] In this embodiment, the peripheral electrode region 301 is composed of metal electrodes and is used to connect to an external circuit, specifically adopting a Ti / Au structure (10 / 80nm Ti / Au). The nanowire region 302 is composed of a 16-pixel MoSi superconducting nanowire array, with each quadrant containing 4 pixels, arranged in a 4×4 array. The nanowire width is ≤150nm, and a polarization-insensitive orthogonal design is adopted, that is, the wiring directions of the nanowires between adjacent pixels are perpendicular to each other, ensuring efficient response to photons of any polarization state. During operation, it is biased below the superconducting critical current. After the nanowire region 302 absorbs photons, local quenching occurs, forming a pulsed electrical signal.

[0081] The Ti / Au bilayer contacts 303 are used for the connection between the nanowire region 302 and the Ti resistor region (304), adopting a 10 / 20nm Ti / Au bilayer structure to achieve a low contact resistance connection between the nanowire and the resistor. The Ti resistor region 304: For each pixel, Ti resistors with resistances of 40Ω, 70Ω, 150Ω, and 200Ω are connected in parallel in series order, as Figure 5As shown in the connection order of R1, R2, R3, and R4. When photons are incident, resistors with different resistance values generate electrical pulse signals with different amplitudes for each pixel, thereby achieving photon number resolution. The solution of this embodiment can output signals with different pulse amplitudes under different click conditions, and the signal-to-noise ratio of the output pulse is greater than the vertical resolution of the oscilloscope. The photon position and number are determined by detecting the signal amplitude. Through the pulse amplitude difference and combined with the calibrated mapping matrix, the target orientation is corrected twice, and the precise position of the light spot within a single quadrant can be further determined, realizing sub-pixel level positioning and improving the device orientation accuracy and sensitivity.

[0082] In an embodiment of the present disclosure, the superconducting nanowire single-photon orientation device further includes: a circuit module for reading out and amplifying the pulsed electrical signal to an identifiable level and outputting it to the data acquisition module.

[0083] In an embodiment of the present disclosure, the circuit module 4 includes a readout circuit module 402 and a cryogenic amplification circuit module 403; the readout circuit module 402 includes Bias-Tee circuits coupled to each quadrant; the Bias-Tee circuit includes a coupling capacitor C, a parallel inductor L s and a shunt resistor R s ; the readout circuit module 402 is used to read out the pulsed electrical signal; the cryogenic amplification circuit module 403 is connected to the output end of the readout circuit module 402 and is used to amplify the pulsed electrical signal to issue an output signal.

[0084] As Figure 3 and Figure 5 shown, in this embodiment, the readout circuit module 402 adopts a symmetric cryogenic PCB design. The four-way circuit reduces the electromagnetic coupling between the four-way signals through a star layout, improving signal integrity; for each quadrant of the four-quadrant superconducting nanowire array, a Bias-Tee circuit composed of a coupling capacitor C, a parallel inductor L s and a 50Ω shunt resistor R s is configured to achieve efficient separation of the pulse signal and the DC bias and can suppress crosstalk. Specifically, the input ends (IN1, IN2, IN3, IN4) of each quadrant are electrically connected to the first end of the shunt resistor R s , the second end of the shunt resistor is electrically connected to the first end of the coupling capacitor C and the second end of the parallel inductor L s , and the second end of the coupling capacitor C is electrically connected to the output end (OUT1, OUT2, OUT3, OUT4) of each quadrant. The output end of each quadrant is connected to the power supply through a bias resistor Z0. The first end of the parallel inductor L s is electrically connected to the current-limiting resistor R bElectrically connected. It should be noted that the output terminals (OUT1, OUT2, OUT3, OUT4) mentioned in this application are relative concepts. For a certain device, relative to the upstream direction of its signal, the port corresponding to the downstream direction of the signal can be referred to as the output terminal, or the interface or port corresponding to the more downstream direction of the signal can also be referred to as the output terminal, that is, the output terminal is relative.

[0085] The readout circuit module outputs the separated pulse signal to the cryogenic amplification circuit module 403 through the SMA interface on the circuit board. The cryogenic amplification circuit module configures a cryogenic low-noise amplifier (WHF-LNA10M-2G) for each quadrant circuit of the detector, with a gain of 35 dB and an operating temperature of 4K, to achieve low-noise amplification of the weak electrical pulse signals output by the quadrant detectors of the quadrant superconducting nanowire single-photon array detection module and improve the signal-to-noise ratio. The amplified signals (output signal 1, output signal 2, output signal 3, output signal 4) are transmitted to the data acquisition and test module 5 at room temperature through the coaxial cable of the vacuum feedthrough 202, and azimuth calculation is performed after ADC digitization.

[0086] In an embodiment of the present disclosure, the circuit module includes a power supply module; the power supply module includes a constant voltage source V b and a current-limiting resistor R b connected in series to form a bias circuit for providing a bias current for the quadrant superconducting nanowire array.

[0087] As Figure 3 and Figure 5 shown, in this embodiment, the circuit module 4 includes a power supply module 401, a readout circuit module 402, and a cryogenic amplification circuit module 403. The specific design and functions are as follows: The power supply module 401 includes a constant voltage source V b and a 10 kΩ current-limiting resistor R b connected in series to form a bias circuit for providing a stable bias current for the quadrant superconducting nanowire single-photon array detection module.

[0088] At the same time, the circuit module 4 also supplies power to the cryogenic amplifier through an independent power supply module. Ensure that the superconducting nanowire array operates below the superconducting critical current to avoid device damage. Independent power supply can ensure the stable operation of the cryogenic amplification circuit module 403 (operating temperature of 4K) and reduce the interference of power supply noise on the signal. The cryogenic amplification module amplifies weak electrical signals and maintains stable gain, and finally outputs pulse signals with a high signal-to-noise ratio to the data acquisition and test module 5 at room temperature through the vacuum feedthrough 202 of the coaxial cable.

[0089] In an embodiment of the present disclosure, as Figure 3The described data acquisition and testing module 5 includes a 12-bit high-speed analog-to-digital converter (ADC) and a counter. The specific design and functions are as follows: The 12-bit high-speed ADC real-time collects and records four-channel pulse signals output by the four-quadrant superconducting nanowire single-photon array detection module to ensure accurate sampling of single-photon pulses. Adaptive threshold adjustment is adopted to reliably capture single-photon pulses. The counter is used to statistically record the pulse amplitude count distribution output by the four ports (OUT1, OUT2, OUT3, OUT4). By measuring, analyzing, and processing the output pulse amplitudes of these four ports, the number of response photons and the photon response positions of the four-quadrant superconducting nanowire single-photon array detection module can be determined, thereby realizing high-precision photon number resolution and position resolution functions and providing support for target azimuth information calculation.

[0090] In an embodiment of the present disclosure, the azimuth detection and processing module 6 is used to calculate the offsets of the centroid of the target light spot on the x-axis and y-axis by the sum-difference method based on the pulse amplitudes and count statistics output by the four ports; the light spot position is re-solved through the pulse amplitude mapping matrix, and the sub-pixel-level deflection angle information is calculated and output.

[0091] In an embodiment of the present disclosure, as Figure 6 shown, all possible 15 pulse amplitude situations in each quadrant recorded by the data acquisition and testing module. Figure 6 a schematically shows the single-pixel response situation, Figure 6 b schematically shows the two-pixel response situation, Figure 6 c schematically shows the three-pixel response situation, Figure 6 d schematically shows the four-pixel response situation. Among them, 1, 2, 3, and 4 respectively represent four pixels connected in series in sequence. When different numbers appear simultaneously, it means that the pixels represented by the numbers detect photons simultaneously. For example, Figure 6 2-48 μV in a represents the pulse response of the second pixel point in this quadrant, and the amplitude is 48 μV; another example is Figure 6 1 4-155 μV in b represents the pulse responses of the first and fourth pixel points in this quadrant, and the amplitude is 155 μV. It can be seen from Figure 6 that there are significant differences in the amplitudes of the output pulse signals generated when different pixels respond. From the lowest amplitude of 31 μV (the amplitude of the unamplified pulse signal) of the single-pixel response to the output pulse of 278 μV corresponding to the simultaneous response of 4 pixels in a single quadrant, this amplitude difference provides an important basis for photon number resolution and position resolution, thereby establishing a mapping relationship between the output pulse amplitude and the number of response photons.

[0092] By comparing the mapping relationship, the number of photons incident on the 16-pixel array and the position information are determined. Here, due to the influence of the coupling capacitance, the output pulse will have different degrees of baseline deviation, that is, the output pulse cannot return to the state where the voltage is 0 after the detector detects a photon. Therefore, when calibrating the output pulse, the amplitude is calculated by subtracting the lowest value of the overshoot from the highest point of the pulse.

[0093] Based on the above superconducting nanowire single-photon detection device, the present disclosure also provides a superconducting nanowire single-photon detection method. The following will continue to be described in detail in combination with Figures 6 - 8 for detailed description.

[0094] Figure 7 Schematically shows a flowchart of a superconducting nanowire single-photon detection method according to an embodiment of the present disclosure. As Figure 7 shown, this embodiment includes:

[0095] In operation S701, receive the diffuse reflection return optical signal of the detected target and convert it into a pulsed electrical signal with amplitude differences;

[0096] In operation S702, amplify the pulsed electrical signal to an identifiable level and issue an output signal;

[0097] In operation S703, count the amplitude count distribution of the output signal;

[0098] In operation S704, based on the counted amplitude count distribution, calculate the spot position through a pulse amplitude mapping matrix and output the deflection angle information.

[0099] The step of receiving the diffuse reflection return optical signal of the detected target and converting it into a pulsed electrical signal with amplitude differences can specifically use a four-quadrant superconducting nanowire single-photon array detection module to receive the diffuse reflection return optical signal of the detected target through a focusing lens and convert it into a pulsed electrical signal with amplitude differences.

[0100] The step of amplifying the pulsed electrical signal to an identifiable level and issuing an output signal can read out the pulsed electrical signal through a set readout circuit module, amplify the pulsed electrical signal to an identifiable level through a cryogenic amplification circuit module, and issue an output signal.

[0101] The step of counting the amplitude count distribution of the output signal can use a data acquisition and testing module to receive the output signal and count the amplitude count distribution.

[0102] The step of calculating the spot position through a pulse amplitude mapping matrix based on the counted amplitude count distribution and outputting the deflection angle information can use an azimuth detection and processing module to calculate the spot position through a pulse amplitude mapping matrix based on the counted amplitude count distribution and output sub-pixel level deflection angle information.

[0103] In one implementation of the present disclosure, calculating the spot position through the pulse amplitude mapping matrix based on the statistical amplitude count distribution includes the following steps: calculating the first offsets of the centroid of the target spot on the x-axis and y-axis by the sum-difference method according to the quadrant pulse counts of the amplitude count distribution.

[0104] In one embodiment of the present disclosure, the method includes:

[0105] Calculating the first offsets of the centroid of the target spot on the x-axis and y-axis by the sum-difference method according to the quadrant pulse counts N1, N2, N3, and N4 of the amplitude count distribution includes:

[0106] Δx = k·[(N1 + N4) – (N2 + N3)] / (N1 + N2 + N3 + N4);

[0107] Δy = k·[(N1 + N2) – (N3 + N4)] / (N1 + N2 + N3 + N4);

[0108] where k is a coefficient related to the spot radius.

[0109] Through the focal length Preliminarily resolving the plane offset into the corresponding target azimuth angle:

[0110] θ x = arctan(Δx / f);

[0111] θy = arctan(Δy / f);

[0112] where f is the distance between the photosensitive surface of the quadrant superconducting nanowire array and the focusing lens.

[0113] In one embodiment of the present disclosure, calculating the spot position through the pulse amplitude mapping matrix and outputting the declination information includes: decoupling the click situation of each quadrant according to the amplitude count distribution, reconstructing the pulse statistical count of each quadrant pixel, constructing a pixel-level amplitude mapping matrix; calculating the second offset of the spot according to the amplitude mapping matrix; calculating the global coordinate offset of the spot position according to the first offset and the second offset; calculating the azimuth angle according to the global coordinate offset; outputting the sub-pixel level declination information.

[0114] In one embodiment of the present disclosure, calculating the spot position through the pulse amplitude mapping matrix and outputting the sub-pixel level declination information includes:

[0115] Decoupling the click situation of each quadrant according to the amplitude count distribution, reconstructing the pulse statistical count of 4 pixels in each quadrant, and constructing a pixel-level amplitude mapping matrix M;

[0116] Calculate the local centroid offset of the light spot in the i-th quadrant, i.e., the second offset (Δx i local , Δy i local );

[0117] ;

[0118] ;

[0119] Calculate the global coordinate offset of the light spot position according to the first offset and the second offset; the global coordinate offset of the calculated light spot position is , ;

[0120] Calculate the corrected azimuth angle as θ x ' = arctan(Δx' / f), θ y ' = arctan(Δy' / f);

[0121] Output sub-pixel level deviation angle information (θ x ', θ y ');

[0122] where the matrix element M ij represents the normalized pulse count at the j-th pixel in the i-th quadrant, and f is the distance between the photosensitive surface of the four-quadrant superconducting nanowire array and the focusing lens.

[0123] In an embodiment of the present disclosure, based on Figure 6 the 15 response pulse amplitudes given in a-d, a detailed analysis is performed on the outputs of Figure 6 the four output ports (OUT1, OUT2, OUT3, OUT4) in e. V(OUT1) - 202 μV, V(OUT2) - 58 μV, V(OUT3) - 158 μV, V(OUT4) - 288 μV respectively represent the output pulse signal amplitudes of the four output ports at a certain moment. By comparing with the above mapping relationship, it is found that the amplitude of V(OUT1) is close to 124 μV in case 124 μV. Therefore, it can be determined that the first quadrant QD-1 corresponding to output port 1 responds to three photons, corresponding to pixels 1, 2, and 4 respectively, at Figure 6In f, the dark blocks represent photons hitting the pixels at those positions. Similarly, V(OUT2) - 58 μV corresponds to the response of the second quadrant QD-2 corresponding to output port 2 to pixel 2, V(OUT3) - 158 μV corresponds to the response of the third quadrant QD-3 corresponding to output port 3 to pixels 1 and 4, and all 4 pixels in the fourth quadrant QD-4 corresponding to V(OUT4) respond. It should be noted that in actual situations, the output amplitude is within a certain range, and the photon number response position can be judged according to the specific range calibrated in the experiment.

[0124] In this embodiment, as Figure 6 shown, based on the statistical amplitude count distribution, the initial azimuth angle is solved, the spot position is corrected through the pulse amplitude mapping matrix, and the sub-pixel level deviation angle information is output. The specific implementation process is as follows.

[0125] 1. Primary solution:

[0126] According to the four-quadrant pulse counts N1, N2, N3, N4 of the amplitude count distribution, the first offsets of the target spot centroid on the x-axis and y-axis are calculated by the sum-difference method:

[0127] Δx = k·[(N1 + N4) – (N2 + N3)] / (N1 + N2 + N3 + N4);

[0128] Δy = k·[(N1 + N2) – (N3 + N4)] / (N1 + N2 + N3 + N4);

[0129] Among them, k is a coefficient related to the spot radius.

[0130] Through the focal length the plane offset is initially solved as the corresponding target azimuth angle:

[0131] θ x = arctan(Δx / f);

[0132] θy = arctan(Δy / f);

[0133] Among them, f is the distance between the photosensitive surface of the four-quadrant superconducting nanowire array and the focusing lens.

[0134] 2. High-precision secondary solution:

[0135] By decoupling the statistical combination of the four-quadrant output pulse amplitudes, the pulse statistical counts of the 4 pixels in each quadrant are reconstructed, and a pixel-level amplitude mapping matrix M is established, where the matrix element M ij represents the normalized pulse count at the jth pixel in the ith quadrant, that is, the probability distribution. It is stipulated that the normalized position coordinates of the 4 pixels in the local coordinate system ( ), taking the first quadrant as an example: Pixel 1 (j = 1): (0.25, 0.75), Pixel 2 (j = 2): (0.75, 0.75), Pixel 3 (j = 3): (0.75, 0.25), Pixel 4 (j = 4): (0.25, 0.25). The pixel arrangement order in each quadrant is the same, and the positive and negative coefficients of each pixel coordinate depend on the quadrant where it is located. The local second offset of the light spot in the i-th quadrant, that is, the centroid offset, is calculated as: , , calculate the global coordinate offset of the light spot position according to the first offset and the second offset; therefore, the global coordinate offset after the secondary correction is calculated as , ; corresponding azimuth angle θ x ’ = arctan(Δx’ / f), θ y ’ = arctan(Δy’ / f).

[0136] As Figure 8 shown, the solid dots represent the central positions of each pixel. According to the finally output sub-pixel level deviation angle information (θ x ’, θ y ’), high-precision light spot positioning and high-sensitivity detection of a long-distance dynamic target are realized.

[0137] Those skilled in the art can understand that the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present disclosure.

[0138] The above describes the embodiments of the present disclosure. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present disclosure.

Claims

1. A superconducting nanowire single-photon detection device, characterized in that: Include: A four-quadrant superconducting nanowire single-photon array detection module is used to receive diffuse reflection echo light signals of the detected target and convert them into pulse electrical signals with amplitude differences; A cryogenic system, used to provide a temperature and vacuum environment less than or equal to a preset value for the four-quadrant superconducting nanowire single-photon array detection module, so that it is in a superconducting state; A circuit module, used to read and amplify the pulse electrical signal to a recognizable level, and output it to a data acquisition module; A data acquisition module, used for calculating the amplitude count distribution based on the pulse electrical signal; The azimuth detection processing module is used to calculate the spot position based on the statistical amplitude count distribution through the pulse amplitude mapping matrix and output the deflection angle information.

2. The device according to claim 1, characterized in that Include: The optical system is used to emit pulsed laser to the detected target, receive diffuse reflection echo light signals of the detected target, and transmit the diffuse reflection echo light signals to the four-quadrant superconducting nanowire single photon array detection module.

3. The device according to claim 1, characterized in that The four-quadrant superconducting nanowire single-photon array detection module includes a 16-pixel superconducting nanowire array, each quadrant includes 4 pixels, and each pixel is connected in parallel with a resistor of different resistance value.

4. The device according to claim 1, characterized in that Include: The power supply module comprises a bias circuit composed of a constant voltage source and a current limiting resistor connected in series, which is used to provide a bias current for the four-quadrant superconducting nanowire single photon array detection module.

5. The device according to claim 1, characterized in that The circuit module includes a readout circuit module; The readout circuit module includes a Bias-Tee circuit coupled to each of the quadrants; the Bias-Tee circuit includes a coupling capacitor C, a parallel inductor L s And shunt resistor R s ; The readout circuit module is used to read out the pulse electrical signal.

6. The device according to claim 2, characterized in that The optical system comprises a pulse laser, which is used to emit pulse laser to the detected target through a polarization controller, an adjustable optical attenuator and a beam expander; The diffuse reflection echo light signal of the detected target is transmitted to the four-quadrant superconducting nanowire single photon array detection module via a telescope, a filter, and an echo reflector.

7. The device according to claim 6, characterized in that The optical system comprises a beam splitter and a flippable reflector; The pulse laser is reflected by the beam splitter part and directed toward the echo reflector via the flip-able reflector to collimate the optical path.

8. A superconducting nanowire single-photon detection method, applied to the superconducting nanowire single-photon detection device of claims 1 to 7, characterized in that: The method comprises: Receive the diffuse reflection echo light signal of the detected target and convert it into a pulse electrical signal with amplitude difference; amplifying the pulse electrical signal to a recognizable level and sending an output signal; Counting the amplitude count distribution of the output signal; Based on the statistical amplitude count distribution, the spot position is calculated through the pulse amplitude mapping matrix, and the deflection angle information is output.

9. The method according to claim 8, characterized in that The step of calculating the spot position based on the statistical amplitude count distribution through a pulse amplitude mapping matrix includes: According to the four-quadrant pulse counts of the amplitude count distribution, the first offset of the target light spot centroid on the x-axis and the y-axis is calculated by the sum-difference method.

10. The method according to claim 9, characterized in that The step of calculating the spot position through the pulse amplitude mapping matrix and outputting the deflection angle information includes: According to the amplitude count distribution, decouple the click situation of each quadrant, reconstruct the pulse statistical count of the pixels in each quadrant, and construct a pixel-level amplitude mapping matrix; Calculate a second offset of the light spot according to the amplitude mapping matrix; Calculate the global coordinate offset of the light spot position according to the first offset and the second offset; Calculating the azimuth according to the global coordinate offset; Output sub-pixel deflection information.

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