Device and method for improving time resolution of single photon detection

Abstract

The invention discloses a device and method for improving the time resolution of single photon detection, and belongs to the field of weak light detection. The device comprises a shaping drive circuit, an avalanche photodiode, a bias voltage source, a 50-ohm resistor, a self-differential extraction circuit and a discrimination timing circuit, and the shaping drive circuit is used for shaping, amplifying and outputting a gating input signal; the avalanche photodiode outputs an avalanche signal containing gating interference; the bias voltage source is used for providing bias voltage for the avalanche photodiode; the 50-ohm resistor provides impedance matching for an avalanche signal; the self-differential extraction circuit is used for removing gating interference so as to extract and amplify an avalanche signal; and the discrimination timing circuit outputs a digital signal. According to the invention, the edge hopping speed of the driving signal is increased, the avalanche duration is reduced, the full width at half maximum of detection counting is compressed, and the time resolution of high-speed single photon detection is improved.

Description

Technical Field

[0001] The present invention belongs to the field of weak light detection, and in particular relates to a device and method for improving the time resolution of single photon detection. Background Art

[0002] High-speed gated single-photon detectors are highly sensitive and time-resolution photoelectric detection devices, specially designed to capture and count single photons in weak light signals. They have broad application prospects in many fields, such as quantum communication: as a key device in quantum key distribution systems, they ensure communication security; high-speed spectral analysis: improve the sensitivity and accuracy of spectral measurement, promote the development of spectroscopy; biomedical imaging, achieve ultra-sensitive fluorescence detection and single-molecule spectral analysis, and promote biomedical research. With the continuous development of science and technology, the performance of high-speed gated single-photon detectors has been continuously improved, and their application fields have become more extensive.

[0003] In infrared high-speed single-photon detectors based on InGaAs / InP avalanche photodiodes (APDs), time resolution is one of the important indicators for evaluating its performance. It is usually defined as the time uncertainty between the incident photon and the corresponding output signal. In the single-photon detection technical indicators, time resolution is measured by the half-width of the detection count, also known as the detector effective count to characterize the time domain of the judgment signal. Time resolution is affected by many factors, including the parameter performance of the APD itself, the gate drive circuit, the avalanche quenching readout circuit, the working conditions of the APD, etc.

[0004] The driving and extraction methods used in high-speed single-photon detectors mainly include sinusoidal gated filtering, harmonic subtraction extraction, and self-differentiation. Sine-gated technology controls the gain and avalanche process of the APD by applying a high-frequency sinusoidal voltage as a gating signal to the APD, which helps to reduce dark counts and background noise. The sinusoidal gated signal is a point frequency in the frequency domain, which is the simplest to implement and process. However, when the gating frequency is further increased, the edge is too slow, which limits the detection time resolution performance, causing the detection results to be misjudged as other cycles; harmonic subtraction technology is complex to implement, requiring multiple harmonic signals to be processed separately, and the drive is also the addition of multiple harmonic signals and then gated to drive the APD tube; self-differential technology effectively suppresses common-mode noise and low-frequency noise through avalanche signal subtraction, enhancing the signal's time resolution and stability. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a device and method for improving the time resolution of single-photon detection. By increasing the edge jump speed of the driving signal, compressing the overvoltage time loaded on the avalanche photodiode, reducing the avalanche duration, and combining the self-differential avalanche signal extraction technology, the compressed detection count half-width is achieved, thereby improving the time resolution of high-speed single-photon detection.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] The present invention proposes a device for improving the time resolution of single-photon detection, comprising: a shaping drive circuit, an avalanche photodiode, a bias voltage, a 50Ω resistor, a self-differential extraction circuit and a discrimination timing circuit. The shaping drive circuit comprises a shaping circuit and a driving circuit, and the gated input signal is connected to the shaping drive circuit. The shaping circuit first realizes the regeneration of the gated input signal to avoid the signal loss during the generation and transmission of the gated input signal, which leads to the decrease in the quality of the gated drive signal caused by the change of the gated input signal. In addition, the shaping circuit realizes the compression of the edge time of the gated input signal; the driving circuit realizes the amplification and output of the shaped signal, and is connected to the cathode of the avalanche photodiode to realize the loading of the gated drive signal of the avalanche photodiode. The avalanche photodiode works in the Geiger mode to realize the high-sensitivity photoelectric detection of the single photon (the smallest quantum of light) signal. The bias voltage is connected to the cathode of the avalanche photodiode to provide the avalanche photodiode with a bias voltage, and the bias voltage is higher than the breakdown voltage to make it work in the Geiger mode. The 50Ω resistor is connected to the anode of the avalanche photodiode to realize the matching of the output impedance of the avalanche signal. The self-differential extraction circuit is connected to the anode of the avalanche photodiode, and includes a self-differential circuit and a signal amplification circuit. The self-differential circuit realizes the difference between the output of the avalanche signal and the output of the non-avalanche signal to extract the avalanche signal, and the signal amplification circuit realizes the amplification of the avalanche signal. The identification timing circuit is connected to the self-differential extraction circuit to realize the determination and identification of the amplified avalanche signal and output a digital signal, and the edge jump time of the digital signal is the generation time of the avalanche signal.

[0008] The present invention provides a method for improving the time resolution of single photon detection, comprising the following steps:

[0009] Shape the gated input signal, compress the edge time, wideband amplify the shaped signal and output it to drive the avalanche photodiode;

[0010] The bias voltage source is used to set the operating point of the avalanche photodiode, detect single photon input, and output an avalanche signal containing gated interference;

[0011] Use 50Ω resistor to provide impedance matching for avalanche signals containing gated interference;

[0012] The gate interference is suppressed and the avalanche signal is extracted through the self-differential technology, and then output to the identification timing circuit after passing through the amplifier;

[0013] The identification timing circuit identifies the avalanche signal and outputs a digital signal.

[0014] The beneficial effects of the present invention are:

[0015] The present invention is based on a method for extracting self-differential avalanche signals, proposes a shaping drive for the gated signal, compresses the detection avalanche time of the avalanche photodiode, and utilizes differential cancellation for the gated interference signal with complex frequency components, which can not only simplify the avalanche signal extraction circuit, but also improve the time resolution performance of single-photon detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural block diagram of a device for improving the time resolution of single-photon detection according to the present invention;

[0017] Figure 2 This is a schematic diagram of a shaping drive circuit of the present invention;

[0018] Figure 3 It is a schematic diagram of the self-differential extraction circuit of the present invention;

[0019] Figure 4 This is a schematic diagram of the avalanche signal identification timing of the present invention;

[0020] Figure 5 The present invention is a flow chart of a method for improving the time resolution of single-photon detection. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] The present invention discloses a device for improving the time resolution of single-photon detection, and proposes a corresponding method based on the device. The gate drive signal is shaped to improve the edge jump speed of the drive signal, and the compression load is applied to the overvoltage gate opening working time of the avalanche photodiode. Then, the avalanche signal self-differential extraction technology is combined to achieve the phase cancellation of the gate signal and its harmonic signal, realize the compression detection counting half-width, and improve the time resolution of the high-speed single-photon detector.

[0023] like Figure 1 As shown, a device for improving the time resolution of single-photon detection proposed by the present invention includes: a shaping drive circuit, an avalanche photodiode, a bias voltage source, a 50Ω resistor, a self-differential extraction circuit and a discrimination timing circuit.

[0024] Wherein, the shaping drive circuit is used to shape, amplify and output the gate input signal;

[0025] The cathode of the avalanche photodiode receives the gated driving signal output by the shaping driving circuit and detects a single photon signal, and outputs an avalanche signal containing gated interference;

[0026] The bias voltage source is connected to the cathode of the avalanche photodiode and is used to provide a bias voltage for the avalanche photodiode;

[0027] The 50Ω resistor is connected to the anode of the avalanche photodiode and is used to provide impedance matching for the avalanche signal containing gated interference output by the avalanche photodiode;

[0028] The self-differential extraction circuit is connected to the anode of the avalanche photodiode and is used to remove the gate interference and extract and amplify the avalanche signal;

[0029] The identification timing circuit is used to determine and identify the amplified avalanche signal and output a digital signal.

[0030] Specifically, the shaping drive circuit includes a shaping circuit and a driving circuit. The gated input signal is connected to the shaping circuit. The shaping circuit first realizes the regeneration of the gated input signal to avoid the signal loss during the generation and transmission of the gated input signal, which leads to the decrease in the quality of the gated drive signal caused by the change of the gated input signal. In addition, the shaping circuit realizes the compression of the edge time of the gated input signal; the driving circuit realizes the amplification and output of the shaped signal, and is connected to the cathode of the avalanche photodiode to realize the loading of the gated drive signal of the avalanche photodiode. The avalanche photodiode works in the Geiger mode to realize the high-sensitivity photoelectric detection of the single photon (the smallest quantum of light) signal, and outputs the avalanche signal containing the gated interference. The bias voltage source is connected to the cathode of the avalanche photodiode to provide a bias voltage, and the bias voltage is higher than the breakdown voltage to make it work in the Geiger mode. The 50Ω resistor is connected to the anode of the avalanche photodiode to achieve the matching of the output impedance of the avalanche signal containing the gated interference. The self-differential extraction circuit is connected to the anode of the avalanche photodiode, and includes a self-differential circuit and a signal amplification circuit. The self-differential circuit realizes the difference between the output of the avalanche signal and the output of the non-avalanche signal to extract the avalanche signal, and the signal amplification circuit realizes the amplification of the avalanche signal. The identification timing circuit is connected to the self-differential extraction circuit to realize the determination and identification of the amplified avalanche signal and output a digital signal, and the edge jump time of the digital signal is the generation time of the avalanche signal.

[0031] A schematic diagram of a shaping drive circuit of a preferred embodiment is shown in FIG. Figure 2 As shown, it includes: a high-speed comparator and a broadband drive amplifier. The gated input signal is isolated by a first capacitor and enters the high-speed comparator for signal regeneration to avoid signal loss during the generation and transmission of the gated input signal, which causes a decrease in the quality of the gated drive signal caused by the change of the gated input signal. At the same time, the high-speed comparator completes the edge shaping of the input signal; and then enters the broadband drive amplifier through the second capacitor. Since the signal after shaping has more frequency components and more high-frequency components, a broadband drive amplifier is required here. Finally, the gated drive signal is output and loaded to the cathode of the avalanche photodiode.

[0032] A schematic diagram of a self-differential extraction circuit of a preferred embodiment is shown in FIG. Figure 3As shown, it includes: a power division circuit, a delay and a differential amplifier circuit. After the avalanche signal containing gated interference is output, it is first divided into two identical signals through the power division circuit, and then the time delay of one of the avalanche signals containing gated interference is realized through the delay circuit. Finally, the gated interference signals of the two signals are cancelled out through the differential amplifier circuit. Here, the delay circuit acts as the two input ends of the differential circuit. When one input is an avalanche signal containing gated interference, the other input has no avalanche signal but only contains the gated interference signal, thereby realizing the differential extraction of the avalanche signal. The avalanche signal is then amplified and output to the identification timing circuit.

[0033] A schematic diagram of a discrimination timing circuit of a preferred embodiment is shown in FIG. Figure 4 As shown, a high-speed comparator is included, and the high-speed comparator is used to identify the timing. One input port is set to the identification level, and the avalanche signal is input to the other input port. When the avalanche signal is higher than the identification level, the output is a high level, and when the avalanche signal is lower than the identification level, the output is a low level. The upper edge jump time is the avalanche signal generation time.

[0034] On the other hand, the present invention provides a method for improving the time resolution of single photon detection. Figure 5 As shown, first, the gated input signal is shaped, the edge time is compressed, the shaped signal is broadband amplified, and the output is loaded to the cathode of the avalanche photodiode; the avalanche photodiode is driven to detect the single photon input, and the avalanche signal containing the gated interference is output; the self-differential technology suppresses the gated interference to extract the avalanche signal, and after passing through the amplifier, it is output to the discrimination timing circuit; through the discrimination timing, the final avalanche signal is output.

[0035] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for improving the temporal resolution of single-photon detection, characterized in that: The device comprises: a shaping drive circuit, an avalanche photodiode, a bias voltage source, a 50Ω resistor, a self-differential extraction circuit and a discrimination timing circuit, wherein: The shaping drive circuit is used to shape, amplify and output the gate input signal; The cathode of the avalanche photodiode receives the gated driving signal output by the shaping driving circuit and detects a single photon signal, and outputs an avalanche signal containing gated interference; The bias voltage source is connected to the cathode of the avalanche photodiode and is used to provide a bias voltage for the avalanche photodiode; The 50Ω resistor is connected to the anode of the avalanche photodiode and is used to provide impedance matching for the avalanche signal containing gated interference output by the avalanche photodiode; The self-differential extraction circuit is connected to the anode of the avalanche photodiode and is used to remove the gate interference to extract and amplify the avalanche signal; The identification timing circuit is used to determine and identify the amplified avalanche signal and output a digital signal.

2. The device for improving the time resolution of single photon detection according to claim 1, characterized in that: The shaping drive circuit includes a shaping circuit and a driving circuit. The gated input signal is connected to the shaping circuit. The shaping circuit regenerates the gated input signal and compresses the edge time of the gated input signal. The driving circuit is used to amplify and output the shaped gated input signal and output it to the cathode of the avalanche photodiode.

3. The device for improving the time resolution of single photon detection according to claim 2, characterized in that: The shaping circuit includes a high-speed comparator, and the driving circuit includes a broadband driving amplifier. The gated input signal is isolated by a first capacitor and enters the high-speed comparator for gated input signal regeneration and edge shaping; then enters the broadband driving amplifier through a second capacitor for amplification, outputs a gated driving signal and is loaded onto the cathode of the avalanche photodiode.

4. The device for improving the time resolution of single photon detection according to claim 1, characterized in that: The self-differential extraction circuit includes a power division circuit, a delay circuit, and a differential amplifier circuit. After the avalanche signal containing gated interference is output, it is first divided into two identical signals through the power division circuit, and then the time delay of one of the avalanche signals containing gated interference is realized through the delay circuit. Finally, the gated interference signal between the two identical signals is cancelled through the differential amplifier circuit, thereby realizing the extraction of the avalanche signal, and then output to the identification timing circuit after amplification.

5. The device for improving the time resolution of single photon detection according to claim 1, characterized in that: The identification timing circuit includes a high-speed comparator, one input port of the high-speed comparator is set to the identification level, and the other input port inputs the avalanche signal. When the avalanche signal is higher than the identification level, the output is a high level, and when the avalanche signal is lower than the identification level, the output is a low level.

6. The device for improving the time resolution of single photon detection according to claim 1, characterized in that: The edge transition time of the output digital signal is the avalanche signal generation time.

7. A method for improving the temporal resolution of single-photon detection, characterized in that: The method comprises: Shape the gated input signal, compress the edge time, wideband amplify the shaped signal and output it to drive the avalanche photodiode; The bias voltage source is used to set the operating point of the avalanche photodiode, detect single photon input, and output an avalanche signal containing gated interference; Use 50Ω resistor to provide impedance matching for avalanche signals containing gated interference; The gate interference is suppressed and the avalanche signal is extracted through the self-differential technology, and then output to the identification timing circuit after passing through the amplifier; The identification timing circuit identifies the avalanche signal and outputs a digital signal.

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