Avalanche signal identification method and single-photon avalanche detector

Abstract

The present disclosure provides an avalanche signal identification method and a single-photon avalanche detector, which can be applied to the fields of signal processing and weak light detection technology. The method includes: generating a gate 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 spike noise; using a balancing module to generate an intermediate balanced signal with the same shape as the spike noise; 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; suppressing the spike noise according to the target balanced signal to generate residual spike noise; 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, and superimposing the position with the largest amplitude of the avalanche signal on the peak position of the residual spike noise; identifying the avalanche signal from the output signal, and the output signal is obtained by superimposing the residual spike noise and the avalanche signal.

Description

Technical Field

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

[0002] Single-photon avalanche detectors (SPADs) can experience false counts due to dark counts caused by thermal excitation and tunneling excitation, as well as afterpulse effects caused by material defects. To reduce false counts caused by dark counts and afterpulse effects, SPADs are typically operated in gated mode. However, because the single-photon avalanche diode (SPAD) in a SPAD is a capacitive device, it charges and discharges at the rising and falling edges of the gate signal, generating spike noise. The avalanche signal occurs within the gate-opening time, meaning it 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 discrimination method in the related art has high requirements for the noise suppression circuit, and the gate 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] Utilizing a single-photon avalanche diode to detect photons within the gate-opening time of the gate signal to generate an avalanche signal and spike noise, wherein the single-photon avalanche diode is connected to the pulse generator;

[0008] 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;

[0009] 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 having the same amplitude as the spike 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 where the avalanche signal has the maximum amplitude 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 spike 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 adjusts 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, 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 identify the avalanche signal from the output signal according to a preset identification 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 spike noise;

[0020] an adjustable capacitor connected to the pulse generator and configured 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, configured to suppress the spike noise according to the target balanced signal to generate residual spike noise;

[0022] a delay module connected to the adjustable capacitor, configured 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 where the amplitude of the avalanche signal is maximum is superimposed on the peak position of the residual spike noise;

[0023] A comparator is connected to the subtractor and is used to identify 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 identify the avalanche signal from the output signal according to a preset identification 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 configured to generate the gating signals having 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 non-inverting 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 amplifier module, connected to the subtractor, and configured to amplify the avalanche signal output by the subtractor;

[0031] a low-pass filtering module, connected to the low-noise amplifying module, and configured to filter the residual spike noise outputted 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 method described above when executed.

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

[0040] According to the embodiments of the present disclosure, due to the existence of residual spike noise, avalanche signals that are 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 the position where the avalanche signal has the largest amplitude is superimposed on the peak position of the residual spike noise, thereby enabling avalanche signals that are much smaller than the residual spike noise to 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 The flowchart of the avalanche signal identification method according to an embodiment of the present disclosure is schematically shown;

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

[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 above-described method 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 merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, 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 well-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 presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0049] 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.

[0050] When expressions such as "at least one of A, B, and C, etc." are used, they should generally be interpreted in accordance with the meaning 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 this disclosure, the collection, updating, analysis, processing, use, transmission, provision, disclosure, and storage of all data involved (including, but not limited to, user personal information) comply with relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures have been taken to prevent unauthorized access to user personal information 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 primarily 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-differentiation, sinusoidal gating, and dual-electrode balancing, but each has its limitations. Self-differentiation requires perfect matching of the two signals in amplitude and delay, sinusoidal gating requires a high-suppression-ratio bandpass filter, and dual-electrode balancing requires nearly identical electrical properties of the two single-photon avalanche diodes. These technologies place stringent demands on the spike noise suppression circuitry.

[0054] Moreover, due to the limitation of the spike noise suppression ratio of the spike noise suppression circuit, residual spike noise will remain. 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. The avalanche signal is located between the residual spike noise. Only avalanche signals with an amplitude greater than the peak value of the residual spike noise can be discriminated and output by the comparator, while avalanche signals 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 discrimination method, comprising: using a pulse generator to generate a gate 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; 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 An electric attenuator is connected to a balancing module; a subtractor is used to suppress spike noise according to a target balanced signal to generate residual spike noise, wherein the subtractor is connected to a single-photon avalanche diode; a delay module is used 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; a comparator is used to identify the avalanche signal from the output signal, wherein the output signal is obtained by superimposing 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 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 spike noise to obtain a target balanced signal with the same amplitude as the spike 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 an 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 a larger amplitude as the external clock signal.

[0069] According to the embodiments of the present disclosure, the single-photon avalanche diode 220 can detect photon signals and generate a corresponding avalanche signal output. However, because the single-photon avalanche diode is a capacitive device, the gate signal coupled to the single-photon diode generates spike noise, which makes the avalanche signal indiscernible and undetectable.

[0070] According to an embodiment of the present disclosure, the balancing module 230 can generate an intermediate balanced signal having the same shape as the spike noise based on the shape of the spike noise. The balancing module can be implemented by, but is not limited to, utilizing capacitor balancing technology, dual-transistor balancing technology, self-differentiation technology, sinusoidal gating technology, and the like.

[0071] According to an embodiment of the present disclosure, the adjustable electrical attenuator 240 can adjust the amplitude of the balancing module so that the amplitudes of the intermediate balanced signal and the spike 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 presence of 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 by 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 allow the position with the largest amplitude of the avalanche signal to be 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 that are 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 the position where the avalanche signal has the largest amplitude is superimposed on the peak position of the residual spike noise, thereby enabling avalanche signals that are much smaller than the residual spike noise to 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 waveforms at different periods in the avalanche signal identification method according to an embodiment of the present disclosure are schematically shown.

[0076] like Figure 3 As shown, Figure 3 (a) in the middle is the gating signal (negative pulse signal) that is generated after the external clock signal passes through the pulse generator and has the same frequency as the external clock signal and a larger amplitude. 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), the avalanche signal is too small and is submerged in the spike noise, making it impossible to identify the avalanche signal. Figure 3 Middle (c) is a waveform diagram of a target balanced signal that is basically consistent with the peak noise, generated by the balancing module and the adjustable electric attenuator. Figure 3 (d) shows the waveform of the subtractor output signal after spike noise is suppressed using the target balanced signal generated by the balancing module. As can be seen, the amplitude of the spike noise is significantly reduced. However, due to differences between the single-photon avalanche diode and the balancing module, the spike noise cannot be completely eliminated; residual spike noise still remains, limiting the ability to identify weak avalanche signals. Figure 3 Figure (e) shows 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 impact of the residual spike noise on the weak avalanche signal is greatly reduced. Figure 3 ×5 in (d) and (e) means that the vertical axis scale is magnified 5 times.

[0077] according to Figure 3 As can be seen, the delay module adjusts the position of the target balanced signal so that the location of the maximum avalanche signal amplitude overlaps the peak position of the residual spike noise. After the delay module is adjusted, a lower discrimination threshold can be set, and the comparator can identify the avalanche signal from the output signal based on the preset discrimination threshold.

[0078] Combine Figure 2 The pulse generator identifies the external clock signal and generates a gate 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) in the figure. 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, as shown in Figure 2. Figure 3 In order to suppress the spike noise, a balanced signal with a shape similar to the spike noise is generated by 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 position of the residual spike noise, the comparator identification threshold can be set to close to zero for avalanche signals, and even very small weak avalanche signals will be identified and output by the comparator, as shown in Figure 5. Figure 3 The disclosed avalanche signal identification method uses residual spike noise to assist in avalanche signal identification, which not only improves the ability to identify weak avalanche signals, but also increases the tolerance to differences between single-photon avalanche diodes and balancing modules, reducing the requirements for spike noise suppression circuits.

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

[0080] Figure 4 The figure schematically shows a circuit diagram of a single-photon avalanche detector according to an embodiment of the present disclosure.

[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 Middle (c) is a waveform diagram of the output signal output from the subtractor, which is a combination of the delayed target balanced signal and the output signal of the single photon avalanche diode 402 .

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

[0083] According to the embodiments of the present disclosure, the single-photon avalanche diode 402 responds to the single-photon signal within the gate-opening time of the gate signal and generates a corresponding avalanche signal output. However, because the single-photon avalanche diode 402 is a capacitive device, the gate signal coupled to the single-photon avalanche diode 402 generates spike noise, which can drown out the avalanche signal. Finally, the output signal of the single-photon avalanche diode 402 is input to the non-inverting terminal of the subtractor 405.

[0084] According to an embodiment of the present disclosure, when the gate signal is coupled to the adjustable capacitor 403, a target balanced signal is generated. By adjusting the capacitance value, the target balanced signal generated by the adjustable capacitor 403 is made substantially consistent with the spike noise generated by the single-photon avalanche diode 402. The two signals are then subtracted by a subtractor 405 to reduce the impact of the spike noise. However, due to differences 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 discern weak avalanche signals.

[0085] According to an 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 with 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, the pulse generator can generate gating signals with the same shape at multiple gating frequencies.

[0089] According to an embodiment of the present disclosure, the low-noise amplifier 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 identify weak avalanche signals.

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

[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 single photons.

[0093] According to an embodiment of the present disclosure, the single-photon avalanche detector 400 operates as follows: an external clock signal is converted into a gated signal with a larger amplitude by a pulse generator 401, and the shape of the gated signal remains essentially 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. By adjusting the size of the adjustable capacitor 403, 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. 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 subtraction through the subtractor 405. However, due to the differences 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 remain. By adjusting the delay module 404, the position where the avalanche signal has the largest amplitude is superimposed on the peak position of the residual spike noise. Since the position where the avalanche signal has the largest amplitude is superimposed on the peak position of the residual spike noise, the avalanche signal discrimination threshold can be set close to zero. Even small avalanche signals will be detected and output, thereby improving detection efficiency and reducing afterpulses.

[0094] Capacitor balancing or dual-transistor balancing methods can achieve adjustable gate frequency, but due to differences in the frequency response of single-photon avalanche diodes and balancing modules, they leave significant residual spike noise. As the gate frequency increases, the number of gate openings increases, giving carriers trapped by material defects more opportunities to be released. This makes the after-pulse effect more significantly affected by the residual spike noise, resulting in the capacitor balancing and dual-transistor balancing methods operating only within a gate frequency range of 100 MHz.

[0095] The single-photon avalanche detectors in the related art can either only extract avalanche signals within the hundreds of megahertz gate frequency adjustment range, or can only extract avalanche signals at a fixed gigahertz gate frequency. There is no single-photon avalanche detector that can extract avalanche signals within the gigahertz gate frequency adjustment range. However, for quantum optics experiments and weak light detection, system performance and flexibility improve with the increase of the gate frequency adjustment range. For example, for some quantum optics experiments, coincidence measurement is 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. The time intervals between adjacent trigger signals are often random and change rapidly, which requires the single-photon avalanche detector to be able 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 discrimination, thereby overcoming the influence of the frequency response difference between the single-photon avalanche diode and the balancing module on avalanche signal discrimination. The pulse generator of the single-photon avalanche detector generates a gated signal with the same shape at different gating frequencies, so the relative position of the avalanche signal and the residual spike noise remains unchanged at different gating frequencies. The avalanche signal discrimination method utilizes the residual spike noise to assist in avalanche signal discrimination, 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 gating frequencies, since the position with the largest avalanche signal amplitude is superimposed on the peak of the residual spike noise, the influence of the frequency response difference between the single-photon avalanche diode and the balancing module on avalanche signal discrimination can be ignored, so the avalanche signal discrimination method disclosed in the present invention increases the gating frequency adjustment range from hundreds of megahertz to gigahertz levels, meeting the needs of quantum optics experiments and weak light detection fields.

[0097] Figure 5 A block diagram of an electronic device suitable for implementing the above-described method according to an embodiment of the present disclosure is schematically shown. Figure 5 The electronic device shown is only an example and should not limit 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 unit 508 into a random access memory (RAM) 503. The processor 501 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 501 may also include 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 the embodiment of the present disclosure.

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

[0100] According to an embodiment of the present disclosure, electronic device 500 may further include an input / output (I / O) interface 505, which is also connected to bus 504. Electronic device 500 may also include one or more of the following components connected to I / O interface 505: an input section 506 including a keyboard, mouse, etc.; an output section 507 including devices such as a cathode ray tube (CRT), liquid crystal display (LCD), and speakers; a storage section 508 including a hard disk; and a communication section 509 including a network interface card such as a LAN card or modem. Communication section 509 performs communication processing via a network such as the Internet. A drive 510 is also connected to I / O interface 505 as needed. Removable media 511, such as a magnetic disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed in drive 510 as needed, so that computer programs read from the removable media can be installed into storage section 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 includes 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 and not be incorporated into the device / apparatus / system. The computer-readable storage medium carries one or more programs, and when executed, implements the method according to the embodiments of the present disclosure.

[0103] According to embodiments of the present disclosure, a computer-readable storage medium may be a non-volatile computer-readable storage medium. Examples include, but are not limited to, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), 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 can be used by or in conjunction 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 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 performed. 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 be stored on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may be transmitted and distributed in the form of a signal on a network medium, downloaded and installed via the communication portion 509, and / or installed from a 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, or any suitable combination thereof.

[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 computer programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C" or similar programming languages. The program code can be executed entirely on the user computing device, partially on the user device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving 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 via the Internet).

[0109] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architectures, 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 can represent a module, program segment, or part of the code, which contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the boxes can also occur in an order different from that marked in the accompanying drawings. For example, two boxes shown 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, as well as the combination of boxes in the block diagram or flowchart, can be implemented using a dedicated hardware-based system that performs the specified functions or operations, or can be implemented using a combination of dedicated hardware and computer instructions. It will be understood by those skilled in the art 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 may be combined and / or coupled in various ways, and all of these combinations and / or couplings fall within the scope of the present disclosure.

[0110] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present disclosure, those skilled in the art may make various 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; Utilizing a single-photon avalanche diode to detect photons within the gate opening time of the gate signal to generate an avalanche signal and 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 spike noise to obtain a target balanced signal having the same amplitude as the spike 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 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 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 includes: The comparator is used to identify the avalanche signal from the output signal according to a preset identification 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 spike noise; an adjustable capacitor connected to the pulse generator, and configured to generate a target 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, configured to suppress the spike noise according to the target balanced signal to generate residual spike noise; a delay module connected to the adjustable capacitor, configured 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 where the avalanche signal has the largest amplitude is superimposed on the peak position of the residual spike noise; A comparator is connected to the subtractor and is used to identify 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 maximum amplitude in the avalanche signal.

6. The single photon avalanche detector according to claim 4, wherein: The comparator is further configured 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: The target balanced signal having the same shape and amplitude as the spike 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 non-inverting 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 configured 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 spike 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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