An apparatus and method for improving time resolution of single photon detection

Abstract

The application discloses a device and method for improving single-photon detection time resolution, and belongs to the field of weak light detection.The device comprises a shaping driving circuit, an avalanche photodiode, a bias voltage source, a 50Ω resistor, a self-difference extraction circuit and a discrimination timing circuit, wherein the shaping driving circuit is used for shaping, amplifying and outputting a gated input signal; the avalanche photodiode outputs an avalanche signal containing gated interference; the bias voltage source provides a bias voltage for the avalanche photodiode; the 50Ω resistor provides impedance matching for the avalanche signal; the self-difference extraction circuit is used for removing gated interference, extracting and amplifying the avalanche signal; and the discrimination timing circuit outputs a digital signal. By improving the edge jump speed of a driving signal and reducing the avalanche duration, the application realizes compression of the half-height width of a detection count, and improves the high-speed single-photon detection time resolution.

Description

Technical Field

[0001] This invention belongs to the field of weak light detection, specifically relating to a device and method for improving the temporal resolution of single-photon detection. Background Technology

[0002] High-speed gated single-photon detectors (HS-GAPs) are highly sensitive, high-time-resolution photoelectric detection devices specifically designed to capture and count individual photons in weak light signals. They have broad application prospects in various fields, such as quantum communication (serving as a key component in quantum key distribution systems to ensure communication security), high-speed spectral analysis (improving the sensitivity and accuracy of spectral measurements and driving the development of spectroscopy), and biomedical imaging (achieving ultrasensitive fluorescence detection and single-molecule spectral analysis, thus advancing biomedical research). With continuous technological advancements, the performance of high-speed gated single-photon detectors is constantly improving, and their application areas are becoming increasingly diverse.

[0003] In high-speed infrared single-photon detectors based on InGaAs / InP avalanche photodiodes (APDs), time resolution is a crucial performance indicator, typically defined as the time uncertainty between the incident photon and the corresponding output signal. In single-photon detection specifications, time resolution is measured by the full width at half maximum (FWHM) of the detector count, also known as the detector effective count, to characterize the time domain of the decision signal. Time resolution is influenced by various factors, including the APD's inherent parameters, the gating drive circuit, the avalanche quenching readout circuit, and the APD's operating conditions.

[0004] The driving and extraction methods used in high-speed single-photon detectors mainly include sinusoidal gating filtering, harmonic subtraction extraction, and self-differential techniques. Sinusoidal gating technology applies a high-frequency sinusoidal voltage to the APD as a gating signal to control the APD's gain and avalanche process, helping to reduce dark counts and background noise. The sinusoidal gating signal is a point frequency in the frequency domain, making it the simplest to implement and process. However, further increasing the gating frequency results in a too-slow edge, limiting the detection time resolution performance and causing the detection result to be misinterpreted as occurring in other periods. Harmonic subtraction technology is complex to implement, requiring the processing of multiple harmonic signals separately, and the driving process involves adding multiple harmonic signals before gating the APD. Self-differential technology effectively suppresses common-mode noise and low-frequency noise by subtracting avalanche signals, enhancing the signal's time resolution and stability. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an apparatus and method for improving the temporal resolution of single-photon detection. By increasing the edge transition speed of the driving signal, the overvoltage time applied to the avalanche photodiode is compressed, the avalanche duration is reduced, and combined with the self-differential avalanche signal extraction technique, the half-width at half-maximum (WHM) of the detection count is compressed, thereby improving the temporal resolution of high-speed single-photon detection.

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

[0007] This invention proposes a device for improving the temporal resolution of single-photon detection, comprising: a shaping and driving circuit, an avalanche photodiode, a bias voltage, a 50Ω resistor, a differential extraction circuit, and a discrimination timing circuit. The shaping and driving circuit includes a shaping circuit and a driving circuit. The gated input signal is connected to the shaping and driving circuit. The shaping circuit first regenerates the gated input signal to avoid signal loss during generation and transmission, thus preventing quality degradation of the gated driving signal caused by changes in the gated input signal. Furthermore, the shaping circuit compresses the edge time of the gated input signal. The driving circuit amplifies and outputs the shaped signal, connecting it to the cathode of the avalanche photodiode to load the gated driving signal. The avalanche photodiode operates in Geiger mode, achieving high-sensitivity photoelectric detection of single photon (the smallest quantum of light) signals. The bias voltage, connected to the cathode of the avalanche photodiode, provides a bias voltage higher than the breakdown voltage, enabling it to operate in Geiger mode. The 50Ω resistor is connected to the anode of the avalanche photodiode to match the output impedance of the avalanche signal. The differential extraction circuit, connected to the anode of the avalanche photodiode, includes a differential circuit and a signal amplification circuit. The differential circuit calculates the difference between the outputs of an avalanche signal and the output of a signal without an avalanche signal to extract the avalanche signal. The signal amplification circuit amplifies the avalanche signal. The discrimination timing circuit, connected to the differential extraction circuit, determines and discriminates the amplified avalanche signal and outputs a digital signal. The edge transition time of the digital signal is the avalanche signal generation time.

[0008] This invention provides a method for improving the temporal resolution of single-photon detection, comprising the following steps:

[0009] The gating input signal is shaped, the edge time is compressed, the shaped signal is wide-band amplified and output to drive the avalanche photodiode;

[0010] The operating point of the avalanche photodiode is set by using a bias voltage source to detect single-photon input and output an avalanche signal containing gated interference.

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

[0012] The gate interference is suppressed and the avalanche signal is extracted by using self-differential technology. After being amplified, the signal is output to the discrimination timing circuit.

[0013] The discrimination timing circuit discriminates and times the avalanche signal and outputs a digital signal.

[0014] The beneficial effects of this invention are as follows:

[0015] This invention proposes a method for extracting avalanche signals based on differential avalanche signals. It proposes a shaping drive for gated signals, compresses the avalanche detection time of avalanche photodiodes, and utilizes differential cancellation for gated interference signals with complex frequency components. This not only simplifies the avalanche signal extraction circuit but also improves the time resolution performance of single-photon detection. Attached Figure Description

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

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

[0018] Figure 3 This 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 discrimination timing of the present invention;

[0020] Figure 5 This is a flowchart of a method for improving the temporal resolution of single-photon detection according to the present invention. Detailed Implementation

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

[0022] This invention discloses a device for improving the temporal resolution of single-photon detection, and proposes a corresponding method. The gating drive signal is shaped to increase the edge transition speed, compressing the overvoltage gate opening time of the avalanche photodiode. Combined with avalanche signal differential extraction technology, the gating signal and its harmonic signals are destructive, thereby compressing the full width at half maximum (FWHM) of the detector count and improving the temporal resolution of the high-speed single-photon detector.

[0023] like Figure 1 As shown, the device for improving the temporal resolution of single-photon detection proposed in this 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] The shaping drive circuit is used to shape, amplify, and output the gated input signal;

[0025] The avalanche photodiode cathode receives the gated drive signal output by the shaping drive circuit and detects a single photon signal, outputting 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 with gated interference output by the avalanche photodiode.

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

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

[0030] Specifically, the shaping drive circuit includes a shaping circuit and a drive circuit. The gated input signal is connected to the shaping circuit, which first regenerates the gated input signal to avoid signal loss during generation and transmission, thus preventing quality degradation of the gated drive signal caused by changes in the gated input signal. Furthermore, the shaping circuit compresses the edge time of the gated input signal. The drive circuit amplifies and outputs the shaped signal, connecting it to the cathode of the avalanche photodiode to load the gated drive signal. The avalanche photodiode operates in Geiger mode, achieving high-sensitivity photodetection of single photon (the smallest quantum of light) signals and outputting an avalanche signal containing gated interference. The bias voltage source, connected to the cathode of the avalanche photodiode, provides a bias voltage higher than the breakdown voltage, enabling it to operate in Geiger mode. The 50Ω resistor is connected to the anode of the avalanche photodiode to match the output impedance of the avalanche signal containing gated interference. The differential extraction circuit, connected to the anode of the avalanche photodiode, includes a differential circuit and a signal amplification circuit. The differential circuit calculates the difference between the outputs of an avalanche signal and the output of a signal without an avalanche signal to extract the avalanche signal. The signal amplification circuit amplifies the avalanche signal. The discrimination timing circuit, connected to the differential extraction circuit, determines and discriminates the amplified avalanche signal and outputs a digital signal. The edge transition time of the digital signal is the avalanche signal generation time.

[0031] A schematic diagram of a shaping drive circuit according to a preferred embodiment is shown below. Figure 2 As shown, it includes a high-speed comparator and a wideband driver amplifier. The gated input signal is blocked by a first capacitor and enters the high-speed comparator for signal regeneration. This avoids signal loss during the generation and transmission of the gated input signal, which would cause a decrease in the quality of the gated drive signal due to changes in the gated input signal. At the same time, the high-speed comparator completes edge shaping of the input signal. The signal then enters the wideband driver amplifier through a second capacitor. Since the shaped signal has more frequency components and more high-frequency components, a wideband driver amplifier is required here. Finally, the gated drive signal is output and applied to the cathode of the avalanche photodiode.

[0032] A schematic diagram of a preferred embodiment of the self-differential extraction circuit is shown below. Figure 3As shown, it includes: a power divider circuit, a delay circuit, and a differential amplifier circuit. After the avalanche signal containing gated interference is output, it is first split into two identical signals by the power divider circuit. Then, the delay circuit is used to delay the time of one of the avalanche signals containing gated interference. Finally, the differential amplifier circuit is used to cancel the gated interference signals of the two signals. Here, the delay circuit acts as the two input terminals of the differential circuit. When one input is an avalanche signal containing gated interference, the other input does not contain an avalanche signal but only a gated interference signal, thus realizing the differential extraction of the avalanche signal. The avalanche signal is then amplified and output to the discrimination timing circuit.

[0033] A schematic diagram of a preferred embodiment of the discrimination timing circuit is shown below. Figure 4 As shown, it includes a high-speed comparator, which is used to discriminate timing. One input port is set to the discrimination level, and the other input port receives the avalanche signal. When the avalanche signal is higher than the discrimination level, the output is high; when the avalanche signal is lower than the discrimination level, the output is low. The upper edge transition time is the avalanche signal generation time.

[0034] On the other hand, the flowchart of a method for improving the temporal resolution of single-photon detection provided by the present invention is as follows: Figure 5 As shown, the gated input signal is first shaped, the edge time is compressed, the shaped signal is wide-band amplified, and the output is loaded onto the cathode of the avalanche photodiode; the avalanche photodiode is driven to detect single-photon input and output an avalanche signal containing gated interference; the gated interference is suppressed by self-differential technology to extract the avalanche signal, and after being amplified, it is output to the discrimination timing circuit; through discrimination timing, the final avalanche signal is output.

[0035] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are 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 within the protection scope of the present invention.

Claims

1. A device for improving the temporal resolution of single-photon detection, characterized in that, The device includes: a shaping drive circuit, an avalanche photodiode, a bias voltage source, a 50Ω resistor, a differential extraction circuit, and a discrimination timing circuit, wherein... The shaping drive circuit is used to regenerate and compress the edge of the gated input signal before outputting it. The avalanche photodiode cathode receives the gated drive signal output by the shaping drive circuit and detects a single photon signal, outputting 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 with gated interference output by the avalanche photodiode. The differential extraction circuit is connected to the anode of the avalanche photodiode and is used to remove gating interference through power division, delay and differential amplification techniques in order to extract and amplify the avalanche signal; The discrimination timing circuit is used to judge and discriminate the amplified avalanche signal and output a digital signal. The edge transition time of the output digital signal is the avalanche signal generation time.

2. The device for improving the temporal resolution of single-photon detection according to claim 1, characterized in that, The shaping driving 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 amplifies and outputs the shaped gated input signal to the avalanche photodiode cathode.

3. The device for improving the temporal 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 wideband driving amplifier. The gated input signal is blocked by a first capacitor and enters the high-speed comparator for gated input signal regeneration and edge shaping. Then, it enters the wideband driving amplifier through a second capacitor for amplification, outputs a gated driving signal, and is applied to the cathode of the avalanche photodiode.

4. The device for improving the temporal resolution of single-photon detection according to claim 1, characterized in that, The differential extraction circuit includes a power divider 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 by the power divider circuit. Then, the delay circuit is used to delay the time of one of the avalanche signals containing gated interference. Finally, the differential amplifier circuit is used to cancel the gated interference signal between the two identical signals, thereby extracting the avalanche signal. After amplification, the signal is output to the discrimination timing circuit.

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

6. A method for improving the temporal resolution of single-photon detection, characterized in that, The method includes: The gating input signal is shaped, the edge time is compressed, the shaped signal is wide-band amplified and output to drive the avalanche photodiode; The operating point of the avalanche photodiode is set by using a bias voltage source to detect single-photon input and output an avalanche signal containing gated interference. A 50Ω resistor is used to provide impedance matching for avalanche signals containing gated interference; The differential extraction circuit suppresses gating interference and extracts avalanche signals through power division, delay and differential amplification techniques, and outputs them to the discrimination timing circuit after amplification; The discrimination timing circuit discriminates and times the avalanche signal, and outputs a digital signal. The edge transition time of the output digital signal is the avalanche signal generation time.

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