Avalanche signal discrimination method and single photon avalanche detector

Abstract

The invention provides an avalanche signal discrimination method and a single photon avalanche detector, which can be applied to the technical field of signal processing and weak light detection. The method comprises the following steps: generating a gating signal; a single photon avalanche diode is used for detecting photons within the door opening time of the gating signal, and an avalanche signal and peak noise are generated; generating an intermediate balance signal with the same shape as the peak noise by using a balance module; using an adjustable electric attenuator to control the amplitude of the intermediate balance signal according to the amplitude of the peak noise so as to obtain a target balance signal having the same amplitude as the peak noise; suppressing the peak noise according to the target balance signal to generate residual peak noise; a time delay module is used for adjusting the target balance signal according to the peak value of the residual peak noise and the peak value of the avalanche signal, and the position with the maximum amplitude of the avalanche signal is superposed on the peak value position of the residual peak noise; and screening an avalanche signal from the output signal, wherein the output signal is obtained by superposing the residual peak noise and the avalanche signal.

Description

Technical Field

[0001] The present disclosure relates to the technical fields of signal processing and weak light detection, and more specifically, to an avalanche signal identification method and a single-photon avalanche detector. Background Art

[0002] Due to dark counts caused by thermal excitation and tunneling excitation and after-pulse effects caused by material defects, single-photon avalanche detectors will have erroneous counts. In order to reduce the erroneous counts caused by dark counts and after-pulse effects, single-photon avalanche detectors usually work in gated mode. However, since the single-photon avalanche diode (SPAD) in the single-photon avalanche detector is a capacitive device, the single-photon avalanche diode will charge and discharge at the rising and falling edges of the gate signal to form spike noise, and the avalanche signal occurs within the gate opening time, that is, the avalanche signal is generated between the spike noise. Therefore, it is necessary to distinguish the avalanche signal from the spike noise.

[0003] In the process of realizing the concept of the present disclosure, the inventors found that there are at least the following problems in the related art: the avalanche signal identification method in the related art has high requirements on the noise suppression circuit, and the gating frequency adjustment range is within the range of hundreds of megahertz. Summary of the invention

[0004] In view of this, the present disclosure provides an avalanche signal identification method and a single-photon avalanche detector.

[0005] One aspect of the present disclosure provides a method for identifying an avalanche signal, comprising:

[0006] A pulse generator is used to generate a gating signal;

[0007] Using a single-photon avalanche diode to detect photons within the gate opening time of the gate signal to generate an avalanche signal and a spike noise, wherein the single-photon avalanche diode is connected to the pulse generator;

[0008] Using a balancing module to generate an intermediate balanced signal having the same shape as the spike noise, wherein the balancing module is connected to the pulse generator;

[0009] Using an adjustable electric attenuator to control the amplitude of the intermediate balanced signal according to the amplitude of the peak noise to obtain a target balanced signal with the same amplitude as the peak noise, wherein the adjustable electric attenuator is connected to the balancing module;

[0010] Using a subtractor to suppress the spike noise according to the target balanced signal to generate residual spike noise, wherein the subtractor is connected to the single photon avalanche diode;

[0011] Using a delay module to adjust the target balanced signal according to the peak value of the residual spike noise and the peak value of the avalanche signal, so that the position with the maximum amplitude of the avalanche signal is superimposed on the peak position of the residual spike noise, wherein the delay module is connected to the adjustable electric attenuator and the subtractor;

[0012] The avalanche signal is identified from the output signal by a comparator, wherein the output signal is obtained by superimposing the residual peak noise and the avalanche signal, and the comparator is connected to the subtractor.

[0013] According to an embodiment of the present disclosure, the delay module is used to adjust the target balance signal according to the peak value of the residual spike noise and the peak value of the avalanche signal, so that the position with the maximum amplitude of the avalanche signal is superimposed on the peak position of the residual spike noise, including:

[0014] The delay module is used to adjust the position of the target balanced signal so that the peak position of the residual spike noise corresponds to the position with the maximum amplitude in the avalanche signal.

[0015] According to an embodiment of the present disclosure, the step of using a comparator to identify the avalanche signal from the output signal includes:

[0016] The comparator is used to discriminate the avalanche signal from the output signal according to a preset discrimination threshold.

[0017] Another aspect of the present disclosure provides a single photon avalanche detector, comprising:

[0018] A pulse generator for generating a gating signal;

[0019] A single photon avalanche diode is connected to the pulse generator and is used to detect photons within the gate opening time of the gate signal to generate an avalanche signal and a spike noise;

[0020] An adjustable capacitor connected to the pulse generator and used to generate an intermediate balanced signal having the same shape and amplitude as the peak noise according to the shape of the peak noise;

[0021] A subtractor, connected to the single photon avalanche diode and the delay module, for suppressing the spike noise according to the target balance signal to generate residual spike noise;

[0022] A delay module, connected to the adjustable capacitor, for adjusting the target balance signal according to the peak value of the residual spike noise and the peak value of the avalanche signal, so that the position with the maximum amplitude of the avalanche signal is superimposed on the peak position of the residual spike noise;

[0023] A comparator is connected to the subtractor and is used to distinguish the avalanche signal from the output signal output by the subtractor, wherein the output signal is obtained by superimposing the residual spike noise and the avalanche signal.

[0024] According to an embodiment of the present disclosure, the delay module is used to adjust the position of the target balanced signal so that the peak position of the residual spike noise corresponds to the position with the maximum amplitude in the avalanche signal.

[0025] According to an embodiment of the present disclosure, the comparator is further configured to discriminate the avalanche signal from the output signal according to a preset discrimination threshold.

[0026] According to an embodiment of the present disclosure, an intermediate balanced signal having the same shape and amplitude as the peak noise is generated by adjusting the capacitance of the adjustable capacitor.

[0027] According to an embodiment of the present disclosure, the pulse generator is used to generate the gating signals with the same shape at multiple gating frequencies.

[0028] According to an embodiment of the present disclosure, the avalanche signal and the spike noise are input to the in-phase terminal of the subtractor, and the target balanced signal adjusted by the delay module is input to the inverting terminal of the subtractor.

[0029] According to an embodiment of the present disclosure, the detector further includes:

[0030] A low noise amplification module, connected to the subtractor, and used to amplify the avalanche signal output by the subtractor;

[0031] A low-pass filtering module, connected to the low-noise amplifying module, for filtering the residual peak noise output by the low-noise amplifying module;

[0032] A temperature control module, used to stabilize the operating temperature of the single photon avalanche diode at a target temperature;

[0033] A DC bias module is connected to the cathode of the single-photon avalanche diode and is used to provide a DC bias voltage for the single-photon avalanche diode, wherein the DC bias voltage is lower than the avalanche breakdown voltage of the single-photon avalanche diode.

[0034] Another aspect of the present disclosure provides an electronic device, comprising:

[0035] one or more processors;

[0036] a memory for storing one or more programs,

[0037] When the one or more programs are executed by the one or more processors, the one or more processors implement the method as described above.

[0038] Another aspect of the present disclosure provides a computer-readable storage medium storing computer-executable instructions, which are used to implement the above method when executed.

[0039] Another aspect of the present disclosure provides a computer program product, which includes computer executable instructions, and when the instructions are executed, are used to implement the method as described above.

[0040] According to the embodiments of the present disclosure, due to the existence of residual spike noise, avalanche signals smaller than the residual spike noise cannot be identified and output. The embodiments of the present disclosure delay the target balanced signal so that the output signal of the single-photon avalanche diode and the target balanced signal can be superimposed on the peak position of the residual spike noise after passing through the subtractor so that avalanche signals far smaller than the residual spike noise can be identified. Compared with the requirements for noise suppression circuits in related technologies, the avalanche signal identification method provided by the embodiments of the present disclosure reduces the requirements for noise suppression circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0042] Figure 1 A flowchart of an avalanche signal identification method according to an embodiment of the present disclosure is schematically shown;

[0043] Figure 2 The application structure diagram of the avalanche identification method according to the embodiment of the present disclosure is schematically shown;

[0044] Figure 3 Schematically showing output waveforms of a single-photon avalanche detector at different times according to an embodiment of the present disclosure;

[0045] Figure 4 A circuit diagram of a single-photon avalanche detector according to an embodiment of the present disclosure is schematically shown; and

[0046] Figure 5 A block diagram of an electronic device suitable for implementing the method described above according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0047] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0048] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0049] All terms (including technical and scientific terms) used herein 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.

[0050] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0051] In the embodiments of the present disclosure, the collection, updating, analysis, processing, use, transmission, provision, disclosure, storage, etc. of the data involved (for example, including but not limited to user personal information) are in compliance with the provisions of relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and maintain the security of user personal information and network security.

[0052] In the embodiments of the present disclosure, the user's authorization or consent is obtained before obtaining or collecting the user's personal information.

[0053] In related technologies, avalanche signal discrimination is mainly achieved by suppressing spike noise. The sensitivity of avalanche signal discrimination is closely related to the spike noise suppression ratio. Spike noise suppression technologies include self-differential technology, sinusoidal gating technology, and dual-tube balanced technology, but each of these technologies has its own limitations. Self-differential technology requires perfect matching of the two signals in amplitude and delay, sinusoidal gating technology requires a bandpass filter with a high suppression ratio, and dual-tube balanced technology requires that the electrical properties of the two single-photon avalanche diodes are almost completely consistent. These technologies place strict requirements on spike noise suppression circuits.

[0054] Moreover, due to the limitation of the suppression ratio of the spike noise suppression circuit, residual spike noise will be left. Due to the existence of the residual spike noise, the discrimination threshold of the comparator must be higher than the peak value of the residual spike noise, and the avalanche signal is located between the residual spike noise. Only the avalanche signal with an amplitude greater than the peak value of the residual spike noise can be discriminated and output by the comparator, while the avalanche signal with an amplitude less than the peak value of the residual spike noise cannot be discriminated.

[0055] In view of this, an embodiment of the present disclosure provides an avalanche signal identification method, including: using a pulse generator to generate a gating signal; using a single-photon avalanche diode to detect photons within the gate opening time of the gating signal to generate an avalanche signal and a spike noise, wherein the single-photon avalanche diode is connected to the pulse generator; using a balancing module to generate an intermediate balanced signal with the same shape as the spike noise, wherein the balancing module is connected to the pulse generator; using an adjustable electric attenuator to control the amplitude of the intermediate balanced signal according to the amplitude of the spike noise to obtain a target balanced signal with the same amplitude as the spike noise, wherein the adjustable The electric attenuator is connected to the balancing module; the spike noise is suppressed according to the target balanced signal by a subtractor to generate residual spike noise, wherein the subtractor is connected to the single-photon avalanche diode; the target balanced signal is adjusted according to the peak value of the residual spike noise and the peak value of the avalanche signal by a delay module, so that the position with the largest amplitude of the avalanche signal is superimposed on the peak position of the residual spike noise, wherein the delay module is connected to the adjustable electric attenuator and the subtractor; the avalanche signal is identified from the output signal by a comparator, wherein the output signal is obtained by superposition of the residual spike noise and the avalanche signal, and the comparator is connected to the subtractor.

[0056] Figure 1 The flowchart of the avalanche signal identification method according to the embodiment of the present disclosure is schematically shown.

[0057] like Figure 1 As shown, the avalanche signal identification method includes operations S110 to S170.

[0058] In operation S110 , a gating signal is generated using a pulse generator.

[0059] In operation S120 , a single-photon avalanche diode is used to detect photons within the gate opening time of the gate signal to generate an avalanche signal and a spike noise, wherein the single-photon avalanche diode is connected to a pulse generator.

[0060] In operation S130 , an intermediate balanced signal having the same shape as the spike noise is generated by using a balancing module, wherein the balancing module is connected to the pulse generator.

[0061] In operation S140, an adjustable electric attenuator is used to control the amplitude of the intermediate balanced signal according to the amplitude of the peak noise to obtain a target balanced signal having the same amplitude as the peak noise, wherein the adjustable electric attenuator is connected to the balancing module.

[0062] In operation S150, a subtractor is used to suppress the spike noise according to the target balanced signal to generate residual spike noise, wherein the subtractor is connected to the single photon avalanche diode.

[0063] In operation S160, the target balanced signal is adjusted according to the peak value of the residual spike noise and the peak value of the avalanche signal by using a delay module, so that the position with the maximum amplitude of the avalanche signal is superimposed on the peak position of the residual spike noise, wherein the delay module is connected to the adjustable electrical attenuator and the subtractor.

[0064] In operation S170, a comparator is used to identify an avalanche signal from an output signal, wherein the output signal is obtained by superimposing the residual spike noise and the avalanche signal, and the comparator is connected to a subtractor.

[0065] For operation S110 to operation S170, the following application structure is proposed. Figure 2 The avalanche identification method according to the embodiment of the present disclosure is introduced.

[0066] Figure 2 The application structure diagram of the avalanche identification method according to the embodiment of the present disclosure is schematically shown.

[0067] like Figure 2 As shown, the application structure 200 includes a pulse generator 210 , a single photon avalanche diode 220 , a balancing module 230 , an adjustable electric attenuator 240 , a delay module 250 , a subtractor 260 and a comparator 270 .

[0068] According to an embodiment of the present disclosure, the pulse generator 210 can identify the external clock signal and generate a gating signal with the same frequency and larger amplitude as the external clock signal.

[0069] According to the embodiment of the present disclosure, the single photon avalanche diode 220 can detect the signal of the photon and generate a corresponding avalanche signal output. However, since the single photon avalanche diode is a capacitive device, the gate signal coupled to the single photon diode will generate spike noise, which makes the avalanche signal unable to be identified and output.

[0070] According to an embodiment of the present disclosure, the balancing module 230 can generate an intermediate balanced signal with the same shape as the peak noise according to the shape of the peak noise. The implementation method of the balancing module includes but is not limited to using capacitor balancing technology, dual-tube balancing technology, self-differential technology, sinusoidal gating technology, etc.

[0071] According to an embodiment of the present disclosure, the adjustable electric attenuator 240 can adjust the amplitude of the balancing module so that the amplitudes of the intermediate balanced signal and the peak noise generated by the balancing module are as consistent as possible, thereby obtaining a target balanced signal.

[0072] According to an embodiment of the present disclosure, the subtractor 260 can subtract the target balanced signal from the spike noise, but since there is actually a difference between the target balanced signal and the spike noise, there will be residual spike noise. The existence of the residual spike noise will limit the discrimination of weak avalanche signals whose amplitude is less than the amplitude of the residual spike noise. Therefore, in order to improve the discrimination ability of weak avalanche signals, the position of the target balanced signal is adjusted through the delay module 250 so that the peak position of the residual spike noise corresponds to the position with the largest amplitude in the avalanche signal, so that the output signal of the single-photon avalanche diode 220 and the target balanced signal can make the position with the largest amplitude of the avalanche signal superimposed on the peak position of the residual spike noise after passing through the subtractor.

[0073] According to an embodiment of the present disclosure, the comparator 270 may identify an avalanche signal by comparing the signal at the peak value according to a preset identification threshold.

[0074] According to the embodiments of the present disclosure, due to the existence of residual spike noise, avalanche signals smaller than the residual spike noise cannot be identified and output. The embodiments of the present disclosure delay the target balanced signal so that the output signal of the single-photon avalanche diode and the target balanced signal can be superimposed on the peak position of the residual spike noise after passing through the subtractor so that avalanche signals far smaller than the residual spike noise can be identified. Compared with the requirements for noise suppression circuits in related technologies, the avalanche signal identification method provided by the embodiments of the present disclosure reduces the requirements for noise suppression circuits.

[0075] Figure 3 The output waveform diagrams at different periods in the avalanche signal identification method according to the embodiment of the present disclosure are schematically shown.

[0076] like Figure 3 As shown, Figure 3 (a) is the external clock signal that, after passing through the pulse generator, generates a gating signal (negative pulse signal) with the same frequency and larger amplitude as the external clock signal. Figure 3 (b) is the waveform of the avalanche signal detected by the single-photon avalanche diode superimposed on the spike noise of the single-photon avalanche diode. Figure 3 As can be seen in (b), since the avalanche signal is too small, it is submerged in the spike noise and cannot be identified. Figure 3 (c) is a waveform diagram of a target balanced signal that is basically consistent with the peak noise, generated by a balancing module and an adjustable electric attenuator. Figure 3 (d) is the waveform of the subtractor output signal after the spike noise is suppressed by the target balanced signal generated by the balancing module. As can be seen from the figure, the amplitude of the spike noise is greatly reduced. However, due to the difference between the single photon avalanche diode and the balancing module, the spike noise cannot be completely eliminated, and residual spike noise still remains, which limits the identification of weak avalanche signals. Figure 3 (e) is the waveform of the subtractor output signal after the target balanced signal is adjusted by the delay module. As can be seen from the figure, by adjusting the delay module, the position where the avalanche signal has the largest amplitude is superimposed on the peak position of the residual spike noise, and the influence of the residual spike noise on the weak avalanche signal is greatly reduced. Figure 3 The ×5 in (d) and (e) means that the vertical axis scale is magnified 5 times.

[0077] according to Figure 3 It can be seen that the delay module can adjust the position of the target balanced signal so that the position with the largest amplitude of the avalanche signal is superimposed on the peak position of the residual spike noise. After adjustment by the delay module, a lower discrimination threshold can be set, and the avalanche signal can be discriminated from the output signal by the comparator according to the preset discrimination threshold.

[0078] Combination Figure 2 The pulse generator identifies the external clock signal and generates a gating signal with the same frequency and larger amplitude as the external clock signal. Its waveform is shown in the figure below. Figure 3 As shown in (a). Subsequently, the gate signal is coupled to the single-photon avalanche diode and the balancing module. During the gate opening time, the single-photon avalanche diode has a certain probability of detecting photons and generating an avalanche signal. However, due to the capacitive effect of the single-photon avalanche diode, the single-photon avalanche diode will generate spike noise at the rising and falling edges of the gate signal, such as Figure 3 In order to suppress the spike noise, a balanced signal with a shape similar to the spike noise is generated through the balancing module, and the amplitude of the target balanced signal and the amplitude of the spike noise are made as consistent as possible by adjusting the adjustable electric attenuator, as shown in (b). Figure 3As shown in (c). The avalanche signal and spike noise output by the single-photon avalanche diode and the target balanced signal are input to the non-inverting terminal and the inverting terminal of the subtractor respectively. Under the action of the target balanced signal, the amplitude of the spike noise of the single-photon avalanche diode is reduced. However, due to the difference between the spike noise and the target balanced signal, residual spike noise will be left at the output of the subtractor. Due to the existence of residual spike noise, the discrimination threshold of the comparator must be higher than the peak value of the residual spike noise, and the avalanche signal is located between the residual spike noise. Weak avalanche signals with an amplitude less than the peak value of the residual spike noise cannot be discriminated, as shown in Figure 3 As shown in (d). In order to further improve the ability to identify weak avalanche signals, the delay module is adjusted so that the position with the largest avalanche signal amplitude is superimposed on the peak position of the residual spike noise. Since the position with the largest avalanche signal amplitude is superimposed on the peak of the residual spike noise, the comparator identification threshold for avalanche signals can be set to close to zero, and even very small weak avalanche signals will be identified and output by the comparator, as shown in Figure 1. Figure 3 The avalanche signal identification method disclosed in the present invention assists in the identification of avalanche signals through residual spike noise, which not only improves the ability to identify weak avalanche signals, but also improves the tolerance of single photon avalanche diodes and balance modules, and reduces the requirements for spike noise suppression circuits.

[0079] In view of the avalanche signal identification method provided in the embodiment of the present disclosure, a single-photon avalanche detector in the gigahertz frequency range is proposed.

[0080] Figure 4 The circuit diagram of the single-photon avalanche detector according to the embodiment of the present disclosure is schematically shown.

[0081] like Figure 4 As shown, the single-photon avalanche detector 400 includes a pulse generator 401, a single-photon avalanche diode 402, an adjustable capacitor 403, a delay module 404, a subtractor 405, a low-noise amplifier module 406, a low-pass filter module 407, a temperature control module 408, a DC bias module 409 and a comparator 410. Figure 4 (a) is the output waveform of the single photon avalanche diode 405. Figure 4 (b) is the output waveform of the target balanced signal after delay. Figure 4 (c) is a waveform diagram of an output signal output from a subtractor consisting of a delayed target balanced signal and an output signal of the single photon avalanche diode 402 .

[0082] According to the embodiment of the present disclosure, the pulse generator 401 can be used to identify the external clock signal, generate a gate signal with the same frequency and larger amplitude as the external clock signal, and the gate signal shape remains basically unchanged for clock signals of different frequencies. The gate signal is divided into two paths, one signal is input to the anode of the single photon avalanche diode 402, and the other signal is input to the adjustable capacitor 403. Under the action of the gate signal, the single photon avalanche diode 402 will be in Geiger mode during the gate opening time.

[0083] According to the embodiment of the present disclosure, the single-photon avalanche diode 402 will respond to the single-photon signal within the gate opening time of the gate signal and generate a corresponding avalanche signal output, but because the single-photon avalanche diode 402 is a capacitive device, the gate signal is coupled to the single-photon avalanche diode 402 to generate spike noise, which will drown the avalanche signal. Finally, the output signal of the single-photon avalanche diode 402 is input to the in-phase terminal of the subtractor 405.

[0084] According to the embodiment of the present disclosure, when the gate signal is coupled to the adjustable capacitor 403, a target balance signal is generated. By adjusting the capacitance value, the target balance signal generated by the adjustable capacitor 403 and the spike noise generated by the single photon avalanche diode 402 are made substantially consistent. Then, the subtractor 405 is used to subtract the signal to reduce the impact of the spike noise. However, due to the difference between the single photon avalanche diode 402 and the adjustable capacitor 403, the spike noise cannot be completely filtered out, leaving residual spike noise, which will limit the detector's ability to discriminate weak avalanche signals.

[0085] According to the embodiment of the present disclosure, the adjustable capacitor is used to simulate the capacitive effect of the single photon avalanche diode. Therefore, by adjusting the capacitance of the adjustable capacitor 403, a target balanced signal having the same shape and amplitude as the spike noise can be generated.

[0086] According to an embodiment of the present disclosure, the delay module 404 can adjust the relative delay between the output signal of the single-photon avalanche diode 402 and the target balanced signal output by the adjustable capacitor 403 so that the position with the maximum amplitude of the avalanche signal is aligned with the peak position of the residual spike noise, thereby improving the ability to distinguish weak avalanche signals.

[0087] According to an embodiment of the present disclosure, the output signal of the subtractor 405 is the input signal at the in-phase end minus the input signal at the in-phase end, the output signal of the single-photon avalanche diode is input to the in-phase end of the subtractor 405, and the target balanced signal after adjustment by the delay module is input to the in-phase end of the subtractor 405.

[0088] According to an embodiment of the present disclosure, a pulse generator may generate gating signals of the same shape at multiple gating frequencies.

[0089] According to the embodiment of the present disclosure, the low noise amplification module 406 is connected to the subtractor 405 and can be used to amplify the avalanche signal output by the subtractor 405 to improve the ability to distinguish weak avalanche signals.

[0090] According to an embodiment of the present disclosure, the low-pass filter module 407 is connected to the low-noise amplifier module 406 and can be used to filter the residual peak noise output by the low-noise amplifier module 406 to improve the sensitivity of avalanche signal discrimination.

[0091] According to an embodiment of the present disclosure, the temperature control module 408 may be used to stabilize the operating temperature of the single photon avalanche diode 402 at a target temperature, thereby reducing the dark count rate.

[0092] According to an embodiment of the present disclosure, the DC bias module 409 is connected to the cathode of the single-photon avalanche diode 402, and can be used to provide a DC bias voltage for the single-photon avalanche diode 402, wherein the DC bias voltage is lower than the avalanche breakdown voltage of the single-photon avalanche diode 402. Under this bias voltage, the single-photon avalanche diode 402 cannot respond to a single photon.

[0093] According to the embodiment of the present disclosure, the single-photon avalanche detector 400 works as follows: the external clock signal is converted into a gated signal with a larger amplitude by the pulse generator 401, and the shape of the gated signal remains basically unchanged for clock signals of different frequencies. The gated signal is then coupled to the single-photon avalanche diode 402 and the adjustable capacitor 403, and the shape and amplitude of the target balanced signal generated by the gated signal coupled to the adjustable capacitor 403 are made as consistent as possible with the spike noise of the single-photon avalanche diode 402 by adjusting the size of the adjustable capacitor 403. The output signals of the single-photon avalanche diode 402 and the adjustable capacitor 403 are respectively input to the in-phase terminal and the inverting terminal of the subtractor 405, and the spike noise of the single-photon avalanche diode 402 is suppressed by subtracting the subtractor 405. However, due to the difference between the single-photon avalanche diode 402 and the adjustable capacitor 403, the spike noise cannot be completely filtered out, and residual spike noise will be left. The position where the avalanche signal has the largest amplitude is superimposed on the position of the peak value of the residual spike noise by adjusting the delay module 404. Since the position where the avalanche signal has the largest amplitude is superimposed on the peak value of the residual spike noise, the discrimination threshold for the avalanche signal can be set close to zero, and even a very small avalanche signal will be discriminated and output, thereby improving the detection efficiency and reducing the after-pulse.

[0094] The gate frequency can be adjusted by using the capacitor balancing method or the dual-tube balancing method, but due to the differences in the single-photon avalanche diode and the balancing module at different frequency responses, a large residual spike noise will be left. As the gate frequency increases, the number of gate openings gradually increases, and the carriers captured by material defects have more opportunities to be released, which makes the post-pulse effect more significantly affected by the residual spike noise, resulting in the capacitor balancing method and the dual-tube balancing method can only work within a gate frequency of hundreds of megahertz.

[0095] Single-photon avalanche detectors in related technologies can either only extract avalanche signals within the hundreds of megahertz gating frequency adjustment range, or can only extract avalanche signals at a fixed gigahertz gating frequency. There is no single-photon avalanche detector that can extract avalanche signals within the gigahertz gating frequency adjustment range. However, for quantum optics experiments and weak light detection, system performance and flexibility increase with the increase of the gating frequency adjustment range. For example, for some quantum optics experiments, coincidence measurements are required. When a single-photon avalanche detector detects a photon, a trigger signal is generated to enable another single-photon avalanche detector to open the door to detect photons, and the time intervals between adjacent trigger signals are often random and change rapidly, which requires the single-photon avalanche detector to operate over a wide frequency range.

[0096] The single-photon avalanche detector disclosed in the present invention takes the capacitance balance method as an example, and utilizes the residual spike noise to assist in avalanche signal identification, thereby overcoming the influence of the frequency response difference between the single-photon avalanche diode and the balance module on the avalanche signal identification. The pulse generator of the single-photon avalanche detector generates a gated signal with the same shape at different gated frequencies, so the relative position of the avalanche signal and the residual spike noise remains unchanged at different gated frequencies. The avalanche signal identification method utilizes the residual spike noise to assist in avalanche signal identification, and can effectively extract the avalanche signal at a low spike noise suppression ratio, thereby reducing the requirements for the spike noise suppression circuit. For different gated frequencies, since the position with the largest avalanche signal amplitude is superimposed on the peak value of the residual spike noise, the influence of the frequency response difference between the single-photon avalanche diode and the balance module on the avalanche signal identification can be ignored, so the avalanche signal identification method disclosed in the present invention increases the gate frequency adjustment range from hundreds of megahertz to gigahertz, meeting the needs of quantum optical experiments and weak light detection.

[0097] Figure 5 A block diagram of an electronic device suitable for implementing the method described above according to an embodiment of the present disclosure is schematically shown. Figure 5 The electronic device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present disclosure.

[0098] like Figure 5As shown, the electronic device 500 according to an embodiment of the present disclosure includes a processor 501, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 502 or a program loaded from a storage part 508 to a random access memory (RAM) 503. The processor 501 may include, for example, a general-purpose microprocessor (such as a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (for example, an application-specific integrated circuit (ASIC)), etc. The processor 501 may also include an onboard memory for caching purposes. The processor 501 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present disclosure.

[0099] In RAM 503, various programs and data required for the operation of electronic device 500 are stored. Processor 501, ROM 502 and RAM 503 are connected to each other via bus 504. Processor 501 performs various operations of the method flow according to the embodiment of the present disclosure by executing the program in ROM 502 and / or RAM 503. It should be noted that the program can also be stored in one or more memories other than ROM 502 and RAM 503. Processor 501 can also perform various operations of the method flow according to the embodiment of the present disclosure by executing the program stored in the one or more memories.

[0100] According to an embodiment of the present disclosure, the electronic device 500 may further include an input / output (I / O) interface 505, which is also connected to the bus 504. The electronic device 500 may further include one or more of the following components connected to the input / output (I / O) interface 505: an input portion 506 including a keyboard, a mouse, etc.; an output portion 507 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage portion 508 including a hard disk, etc.; and a communication portion 509 including a network interface card such as a LAN card, a modem, etc. The communication portion 509 performs communication processing via a network such as the Internet. A drive 510 is also connected to the input / output (I / O) interface 505 as needed. A removable medium 511, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 510 as needed, so that a computer program read therefrom is installed into the storage portion 508 as needed.

[0101] According to an embodiment of the present disclosure, the method flow according to an embodiment of the present disclosure can be implemented as a computer software program. For example, an embodiment of the present disclosure includes a computer program product, which includes a computer program carried on a computer-readable storage medium, and the computer program contains a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 509, and / or installed from the removable medium 511. When the computer program is executed by the processor 501, the above-mentioned functions defined in the system of the embodiment of the present disclosure are executed. According to an embodiment of the present disclosure, the system, equipment, device, module, unit, etc. described above can be implemented by a computer program module.

[0102] The present disclosure also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or may exist independently without being assembled into the device / apparatus / system. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the method according to the embodiment of the present disclosure is implemented.

[0103] According to an embodiment of the present disclosure, the computer-readable storage medium may be a non-volatile computer-readable storage medium. For example, it may include, but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, apparatus, or device.

[0104] For example, according to an embodiment of the present disclosure, the computer-readable storage medium may include the ROM 502 and / or the RAM 503 described above and / or one or more memories other than the ROM 502 and the RAM 503 .

[0105] An embodiment of the present disclosure also includes a computer program product, which includes a computer program, and the computer program contains a program code for executing the method provided by the embodiment of the present disclosure. When the computer program product runs on an electronic device, the program code is used to enable the electronic device to implement the avalanche signal identification method provided by the embodiment of the present disclosure.

[0106] When the computer program is executed by the processor 501, the above functions defined in the system / device of the embodiment of the present disclosure are executed. According to the embodiment of the present disclosure, the system, device, module, unit, etc. described above can be implemented by a computer program module.

[0107] In one embodiment, the computer program may rely on tangible storage media such as optical storage devices, magnetic storage devices, etc. In another embodiment, the computer program may also be transmitted and distributed in the form of signals on a network medium, and downloaded and installed through the communication part 509, and / or installed from the removable medium 511. The program code contained in the computer program may be transmitted using any appropriate network medium, including but not limited to: wireless, wired, etc., or any suitable combination of the above.

[0108] According to an embodiment of the present disclosure, the program code for executing the computer program provided by the embodiment of the present disclosure can be written in any combination of one or more programming languages. Specifically, these computing programs can be implemented using high-level process and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, Java, C++, python, "C" language or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on the remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device can be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computing device (for example, using an Internet service provider to connect through the Internet).

[0109] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present disclosure can be combined and / or combined in a variety of ways, even if such a combination or combination is not explicitly recorded in the present disclosure. In particular, without departing from the spirit and teaching of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0110] The embodiments of the present disclosure are described above. 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 above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A method for identifying an avalanche signal, comprising: A pulse generator is used to generate a gating signal; Using a single photon avalanche diode to detect photons within the gate opening time of the gate signal to generate an avalanche signal and a spike noise, wherein the single photon avalanche diode is connected to the pulse generator; generating an intermediate balanced signal having the same shape as the spike noise by using a balancing module, wherein the balancing module is connected to the pulse generator; Using an adjustable electric attenuator to control the amplitude of the intermediate balanced signal according to the amplitude of the peak noise to obtain a target balanced signal having the same amplitude as the peak noise, wherein the adjustable electric attenuator is connected to the balancing module; Using a subtractor to suppress the spike noise according to the target balanced signal to generate residual spike noise, wherein the subtractor is connected to the single photon avalanche diode; Using a delay module to adjust the target balanced signal according to the peak value of the residual spike noise and the peak value of the avalanche signal, so that the position with the maximum amplitude of the avalanche signal is superimposed on the peak position of the residual spike noise, wherein the delay module is connected to the adjustable electric attenuator and the subtractor; The avalanche signal is identified from the output signal by using a comparator, wherein the output signal is obtained by superimposing the residual spike noise and the avalanche signal, and the comparator is connected to the subtractor.

2. The method according to claim 1, wherein: The method of using the delay module to adjust the target balance signal according to the peak value of the residual spike noise and the peak value of the avalanche signal so that the position where the avalanche signal has the largest amplitude is superimposed on the peak position of the residual spike noise includes: The delay module is used to adjust the position of the target balanced signal so that the peak position of the residual spike noise corresponds to the position with the maximum amplitude in the avalanche signal.

3. The method according to claim 1, wherein: The step of using a comparator to identify the avalanche signal from the output signal comprises: The comparator is used to discriminate the avalanche signal from the output signal according to a preset discrimination threshold.

4. A single photon avalanche detector, comprising: A pulse generator for generating a gating signal; A single photon avalanche diode is connected to the pulse generator and is used to detect photons within the gate opening time of the gate signal to generate an avalanche signal and a spike noise; an adjustable capacitor connected to the pulse generator and used to generate an intermediate balanced signal having the same shape and amplitude as the peak noise according to the shape of the peak noise; A subtractor, connected to the single photon avalanche diode and the delay module, for suppressing the spike noise according to the target balanced signal to generate residual spike noise; A delay module, connected to the adjustable capacitor, for adjusting the target balance signal according to the peak value of the residual spike noise and the peak value of the avalanche signal, so that the position with the maximum amplitude of the avalanche signal is superimposed on the peak position of the residual spike noise; A comparator is connected to the subtractor and is used to distinguish the avalanche signal from the output signal output by the subtractor, wherein the output signal is obtained by superimposing the residual spike noise and the avalanche signal.

5. The single photon avalanche detector according to claim 4, wherein: The delay module is used to adjust the position of the target balanced signal so that the peak position of the residual spike noise corresponds to the position with the largest amplitude in the avalanche signal.

6. The single photon avalanche detector according to claim 4, wherein: The comparator is further used to identify the avalanche signal from the output signal according to a preset identification threshold.

7. The single photon avalanche detector according to claim 4, wherein: An intermediate balanced signal having the same shape and amplitude as the peak noise is generated by adjusting the capacitance of the adjustable capacitor.

8. The single photon avalanche detector according to any one of claims 4 to 7, wherein: The pulse generator is used to generate the gating signals with the same shape at multiple gating frequencies.

9. The single photon avalanche detector according to any one of claims 4 to 7, wherein: The avalanche signal and the spike noise are input to the in-phase terminal of the subtractor, and the target balanced signal adjusted by the delay module is input to the inverting terminal of the subtractor.

10. The single photon avalanche detector according to any one of claims 4 to 7, further comprising: A low noise amplification module, connected to the subtractor, and used to amplify the avalanche signal output by the subtractor; A low-pass filtering module, connected to the low-noise amplifying module, and configured to filter the residual peak noise output by the low-noise amplifying module; A temperature control module, used to stabilize the operating temperature of the single photon avalanche diode at a target temperature; A DC bias module is connected to the cathode of the single-photon avalanche diode and is used to provide a DC bias voltage for the single-photon avalanche diode, wherein the DC bias voltage is lower than the avalanche breakdown voltage of the single-photon avalanche diode.

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