An upconversion single-photon detector and an upconversion single-photon detection system

Abstract

The application relates to an up-conversion single-photon detector and an up-conversion single-photon detection system, which comprise a single-photon detection component, a power stabilization component and a controller. The single-photon detection component comprises a detection circuit. The power stabilization component comprises a beam splitter, a first photodiode, a temperature control device and an operational amplifier circuit. The input end of the beam splitter is used for connecting a pump laser. The first output end of the beam splitter is used for connecting a frequency up-conversion waveguide. The second output end of the beam splitter is connected with the light-sensing part of the first photodiode. The first photodiode is arranged in the temperature control device. The operational amplifier circuit is connected with the first photodiode in a sampling mode. The output end of the operational amplifier circuit is connected with the controller. The controller is used for controlling the pump laser according to the collected signal. The temperature control device is used for controlling the temperature around the first photodiode, so as to reduce the influence of the surrounding environment, especially the temperature, on the first photodiode, improve the accuracy of the output voltage signal, and further improve the stability of the up-conversion single-photon detection.

Description

Technical Field

[0001] This application relates to the field of single-photon detection technology, and in particular to an upconversion single-photon detector and an upconversion single-photon detection system. Background Technology

[0002] A single-photon detector is an ultra-low noise device with extremely high sensitivity and resolution. It can detect and count the smallest energy quantum of light—the photon—and is widely used in quantum communication, quantum computing, biomedical imaging and other fields.

[0003] Currently, near-infrared single-photon detection technologies mainly include superconducting nanowire single-photon detectors, upconversion single-photon detectors, and InGaAs / InP single-photon detectors. Superconducting nanowire detectors require extremely low temperatures to ensure high detection efficiency and low dark counts, limiting their size. InGaAs / InP detectors, limited by their material properties, exhibit relatively poor detection efficiency, afterpulse probability, and saturation count rate, and may experience distortion under strong lidar light. Existing technologies suffer from low detection efficiency for single-photon detectors, and the lack of system-level and product-level upconversion single-photon detectors severely hinders the promotion and application of this technology.

[0004] Laser power stability affects the signal-to-noise ratio of the detection signal, and the resulting laser power stability has become a major concern. Generally, feedback is obtained by detecting the optical signal and the pump laser is controlled by a PID algorithm to achieve power stability. However, when using a single-photon detector to detect the pump laser, the detection optical signal is affected by the environment and generates some noise, which affects the accuracy of stable control of the pump laser.

[0005] Therefore, how to provide an improved system for stabilizing optical signals to reduce optical signal detection noise and improve the power stability of pump lasers has become an urgent problem to be solved. Utility Model Content

[0006] In view of this, embodiments of this application provide an upconversion single-photon detector and an upconversion single-photon detection system to solve the problem of how to provide an improved system for stabilizing the detection optical signal, thereby reducing optical signal detection noise and improving the power stability of the pump laser.

[0007] In a first aspect, this application provides an upconversion single-photon detector, including a single-photon detection component, a power stabilization component, and a controller for connecting the output end of a frequency upconversion waveguide;

[0008] The single-photon detection component includes a detection circuit, which is used to collect the optical signal output from the output terminal of the frequency up-conversion waveguide and convert the optical signal into a detection signal and send it to the controller.

[0009] The power stabilization component includes a beam splitter, a first photodiode, a temperature control device, and an operational amplifier circuit. The input terminal of the beam splitter is used to connect to a pump laser, the first output terminal of the beam splitter is used to connect to the frequency up-conversion waveguide, and the second output terminal of the beam splitter is connected to the photosensitive part of the first photodiode, so as to adjust the current passing through the first photodiode according to the light from the second output terminal of the beam splitter.

[0010] The first photodiode is disposed in the temperature control device. The operational amplifier circuit is connected to the first photodiode for sampling. The output terminal of the operational amplifier circuit is connected to the controller to collect the current passing through the first photodiode and convert the current into a voltage signal to feed the voltage signal back to the controller.

[0011] The controller is used to control the pump laser based on the detection signal and the voltage signal.

[0012] In one embodiment, the temperature control device includes a temperature sensor and a first temperature control device. The first temperature control device is provided with the first photodiode to control the ambient temperature of the first photodiode. The temperature sensor is provided around the first photodiode to collect the ambient temperature of the first photodiode.

[0013] In one embodiment, the first temperature control device includes at least two copper plates, one of which is provided with a first semiconductor cooling chip, the first photodiode is disposed on the copper plate provided with the first semiconductor cooling chip, and the first photodiode is covered by another copper plate.

[0014] In one embodiment, each thermoelectric cooler is connected to the controller to control the temperature of the temperature control device according to the control instructions of the controller, and the temperature sensor is connected to the controller to send the collected temperature to the controller.

[0015] In one embodiment, a sampling circuit is further included, the sampling circuit employing a shielded twisted-pair cable, and the operational amplifier circuit is connected to the first photodiode through the sampling circuit.

[0016] In one embodiment, the detection circuit includes a detection line, a comparator, a trigger, a counting output module, an active quenching module, a delay chip, and a fast recovery module;

[0017] The detection circuit includes a silicon avalanche photodiode, a sampling resistor, and a quenching resistor connected in series. One end of the sampling resistor is connected to the power supply, and the other end of the sampling resistor is connected to the cathode of the avalanche photodiode. The cathode of the avalanche photodiode is connected to the input of the comparator.

[0018] The output of the comparator is connected to the input of the flip-flop, the output of the flip-flop is connected to the input of the counting output module, the output of the flip-flop is connected to the input of the active quenching module, the output of the active quenching module is connected to the anode of the avalanche photodiode, the output of the flip-flop is connected to the input of the delay chip, the output of the delay chip is connected to the input of the fast recovery module, the output of the fast recovery module is connected to the common terminal of the quenching resistor, and the first end of the quenching resistor is connected to the anode of the avalanche photodiode.

[0019] In one embodiment, the controller includes an ADC circuit, an FPGA circuit, and a DAC circuit. One end of the ADC circuit is connected to one end of the FPGA circuit, and the other end of the ADC circuit is connected to the output terminal of the operational amplifier circuit. The other end of the FPGA circuit is connected to one end of the DAC circuit, and the other end of the DAC circuit is connected to the pump laser and the temperature control device.

[0020] In one embodiment, the controller further includes a temperature acquisition module and a temperature regulation module;

[0021] The input terminal of the temperature acquisition module is connected to the avalanche photodiode to acquire the current temperature of the avalanche photodiode, and the output terminal of the temperature acquisition module is connected to the ADC circuit to transmit the current temperature to the FPGA circuit.

[0022] The input terminal of the temperature regulation module is connected to the FPGA circuit through the DAC circuit, and the output terminal of the temperature regulation module is connected to a second temperature control device for regulating the temperature of the avalanche photodiode. The FPGA circuit is used to control the second temperature control device according to the current temperature.

[0023] In one embodiment, the controller further includes a voltage regulation module and a filtering module. The input terminal of the voltage regulation module is connected to the FPGA circuit through the DAC circuit, the output terminal of the voltage regulation module is connected to the second terminal of the quenching resistor, and the filtering module is disposed between the voltage regulation module and the quenching resistor.

[0024] Secondly, this application provides an upconversion single-photon detection system, which includes a host computer, a seed source, a pump laser, a frequency upconversion waveguide, and an upconversion single-photon detector as described in the first aspect and its improvements. The seed source is connected to the pump laser, the pump laser is connected to the frequency upconversion waveguide through a beam splitter in the upconversion single-photon detector, the frequency upconversion waveguide is connected to the single-photon detection component in the upconversion single-photon detector, and the host computer is connected to the controller of the upconversion single-photon detector.

[0025] The advantages of this application compared to the prior art are as follows: The system of this application includes a single-photon detection component, a power stabilization component, and a controller for connecting the output end of a frequency up-conversion waveguide; the single-photon detection component includes a detection circuit, which is used to collect the optical signal output from the output end of the frequency up-conversion waveguide and convert the optical signal into a detection signal to be sent to the controller; the power stabilization component includes a beam splitter, a first photodiode, a temperature control device, and an operational amplifier circuit; the input end of the beam splitter is used to connect to a pump laser; the first output end of the beam splitter is used to connect to the frequency up-conversion waveguide; the second output end of the beam splitter is connected to the photosensitive part of the first photodiode to adjust the current passing through the first photodiode according to the light from the second output end of the beam splitter; the first photodiode is disposed in the temperature control device; the operational amplifier circuit is connected to the first photodiode for sampling; the output end of the operational amplifier circuit is connected to the controller to collect the current passing through the first photodiode and convert the current into a voltage signal to be fed back to the controller; the controller is used to control the pump laser according to the detection signal and the voltage signal. The temperature around the first photodiode is controlled by a temperature control device to reduce the influence of the surrounding environment, especially temperature, on the first photodiode, improve the accuracy of the output voltage signal, and thus improve the stability of upconversion single-photon detection. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of an upconversion single-photon detection system provided in an embodiment of this application;

[0028] Figure 2 This is a schematic diagram of the structure of an operational amplifier zero-bias circuit provided in one embodiment of this application;

[0029] Figure 3This is a schematic diagram of the structure of a single-photon detection component provided in one embodiment of this application;

[0030] Figure 4 This is a schematic diagram of the connection between a controller and a single-photon detection component provided in an embodiment of this application. Detailed Implementation

[0031] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0032] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0033] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0034] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0035] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0037] To illustrate the technical solution of this application, specific embodiments are described below.

[0038] like Figure 1 The diagram shown is a structural schematic of an upconversion single-photon detection system provided in this application. The system includes a host computer, a seed source, a pump laser, a frequency upconversion waveguide, and an upconversion single-photon detector. The seed source is connected to the pump laser, which is connected to the frequency upconversion waveguide via a beam splitter in the upconversion single-photon detector. The frequency upconversion waveguide is connected to the single-photon detection component in the upconversion single-photon detector, and the host computer is connected to the controller of the upconversion single-photon detector. The seed source, pump laser, beam splitter, frequency upconversion waveguide, and upconversion single-photon detector are sequentially connected in the direction of light propagation. Further, the frequency upconversion waveguide can be a ridged frequency upconversion waveguide such as a PPLN.

[0039] exist Figure 1 The upconversion single-photon detector includes a single-photon detection component for connecting to the output end of the frequency upconversion waveguide, a power stabilization component, and a controller. The single-photon detection component includes a detection circuit, which is used to acquire the optical signal output from the output end of the frequency upconversion waveguide and convert the optical signal into a detection signal and send it to the controller.

[0040] The power stabilization component includes a beam splitter, a first photodiode, a temperature control device, and an operational amplifier circuit. The input terminal of the beam splitter is used to connect to the pump laser, the first output terminal of the beam splitter is used to connect to the frequency up-conversion waveguide, and the second output terminal of the beam splitter is connected to the photosensitive part of the first photodiode to adjust the current passing through the first photodiode according to the light from the second output terminal of the beam splitter. The first photodiode is disposed in the temperature control device. The operational amplifier circuit is connected to the first photodiode for sampling, and the output terminal of the operational amplifier circuit is connected to the controller to collect the current passing through the first photodiode and convert the current into a voltage signal to feed back the voltage signal to the controller. The controller is used to control the pump laser according to the detection signal and the voltage signal.

[0041] In this embodiment, the temperature around the first photodiode is controlled by a temperature control device to reduce the influence of the surrounding environment, especially temperature, on the first photodiode, improve the accuracy of the output voltage signal, and thus improve the stability of upconversion single-photon detection.

[0042] The optical path begins with the seed source, whose output optical signal is amplified by the pump laser and then split into two parts by the beam splitter. One part enters the frequency up-conversion waveguide and serves as the main optical path, which is then output to the single-photon detection component. The other small part serves as feedback to the first photodiode, which is placed on a temperature control device.

[0043] In addition, the controller includes an ADC circuit, an FPGA circuit, and a DAC circuit. One end of the ADC circuit is connected to one end of the FPGA circuit, and the other end of the ADC circuit is connected to the output of the operational amplifier circuit. The other end of the FPGA circuit is connected to one end of the DAC circuit, and the other end of the DAC circuit is connected to the pump laser and the temperature control device. The FPGA circuit is connected to a host computer via a serial port for real-time system monitoring and parameter interaction to ensure its normal operation. Specifically, the FPGA circuit controls the temperature of the frequency up-conversion waveguide through a frequency up-conversion control module, controls the current of the pump laser through a pump laser control module, and controls the seed source through a seed source control module.

[0044] In one embodiment, the temperature control device includes a temperature sensor and a first temperature control unit. A first photodiode is disposed on the first temperature control unit to control the ambient temperature of the first photodiode. The temperature sensor is disposed around the first photodiode to collect the ambient temperature. By detecting the ambient temperature using the temperature sensor, the first temperature control unit can be accurately controlled based on the ambient temperature, for example, controlling the ambient temperature to approximately 25°C.

[0045] In one embodiment, the temperature sensor is a thermistor temperature coefficient (NTC) sensor, which can reduce the overall size of the device and accurately collect temperature information.

[0046] In one embodiment, the first temperature control device includes at least two copper plates. A thermoelectric cooler (TEC) is disposed on one of the copper plates. A first photodiode is disposed on the copper plate with the first TEC, and the first photodiode is covered by another copper plate. Placing the first photodiode on one copper plate, while also covering its upper part with a copper plate, facilitates heat conduction and ensures temperature uniformity across the entire first photodiode. Finally, the TEC controls the temperature of the copper plate, ensuring a consistent temperature within the operating temperature range. For example, the TEC maintains a constant temperature of 25°C within the operating temperature range, thus ensuring that the responsivity of the first photodiode does not change with variations in ambient temperature.

[0047] In one embodiment, each thermoelectric cooler is connected to a controller to control the temperature of the temperature control device according to the controller's control commands. A temperature sensor is connected to the controller to send the collected temperature data to the controller. The controller that controls the pump laser can be connected to the temperature control device for temperature control; alternatively, the temperature control device can be controlled by an independent controller.

[0048] In one embodiment, a sampling circuit is also included. The sampling circuit uses shielded twisted-pair cable, and the operational amplifier circuit is connected to the first photodiode through the sampling circuit. Since the current generated by the first photodiode is a small signal, even slight external interference can cause a significant change in the output optical power. Therefore, using shielded twisted-pair cable can minimize EMC interference.

[0049] In one embodiment, the operational amplifier circuit is either a zero-bias operational amplifier circuit or an over-bias operational amplifier circuit. Figure 2 shows a schematic diagram of the zero-bias operational amplifier circuit provided in this embodiment, which is an operational amplifier chip and its components used for converting the current of the first photodiode to voltage and amplifying the voltage. The first photodiode is a current-type device, requiring the current signal to be converted into a detectable voltage signal and amplified. The operational amplifier chip itself has a certain amount of noise; therefore, a low-noise chip model is selected here. A low-noise operational amplifier chip refers to an amplifier with extremely low internal noise levels, typically a few nV / Hz. Its purpose is to minimize the additional noise introduced by itself when amplifying weak current or voltage signals.

[0050] Figure 2 illustrates a complete signal transmission path: the current signal from the first photodiode flows through a feedback resistor, is converted into a voltage by a low-noise operational amplifier (LNP), amplified, and then converted into a digital signal by an ADC and output to a digital processor. The LNP and precision resistors ensure the accuracy of signal conversion and amplification, while the ADC performs a high-fidelity conversion from analog to digital.

[0051] In addition, there are generally two driving methods for the first photodiode: biased and zero biased. When the biased method is used, the first photodiode has a fast response speed but high noise. The zero biased method sacrifices the response speed but has low system noise. This zero biased method is the preferred option for frequency-conversion pumped lasers with a closed-loop response speed of several hundred Hz.

[0052] The output of the first photodiode is amplified by connecting to a zero-bias operational amplifier circuit via a shielded twisted-pair cable. Finally, the signal is processed by the FPGA. The FPGA runs a PID algorithm to calculate the difference between the signal sampled by the ADC and the actual value that needs to be achieved. Finally, the output optical power is stabilized by controlling the pump laser current through the DAC.

[0053] This application employs precise temperature control of the first photodiode to ensure that the output optical power does not change significantly when the ambient temperature changes. Furthermore, it uses shielded twisted-pair cable to minimize external interference, and employs low-noise operational amplifiers and matching zero-bias circuitry to minimize the circuit's own noise and improve the stability of the output power.

[0054] like Figure 3 The diagram shows a schematic of a single-photon detection component provided in this application. The detection circuit includes a detection line, a comparator, a trigger, a counting output module, an active quenching module, a delay chip, and a fast recovery module. A silicon avalanche photodiode, a sampling resistor, and a quenching resistor are connected in series in the detection line. One end of the sampling resistor is connected to the power supply, and the other end is connected to the cathode of the avalanche photodiode. The cathode of the avalanche photodiode is connected to the input of the comparator. The output of the comparator is connected to the input of the trigger, the output of the trigger is connected to the input of the counting output module, the output of the trigger is connected to the input of the active quenching module, the output of the active quenching module is connected to the anode of the avalanche photodiode, the output of the trigger is connected to the input of the delay chip, the output of the delay chip is connected to the input of the fast recovery module, the output of the fast recovery module is connected to the common terminal of the quenching resistor, and the first end of the quenching resistor is connected to the anode of the avalanche photodiode.

[0055] Furthermore, the comparator in this embodiment is a high-speed comparator, and the flip-flop in this embodiment is a D flip-flop with reset and set functions. The action signal output from the detection line flows to the non-inverting input of the high-speed comparator, the inverting input of the high-speed comparator is connected to the discrimination level, the non-inverting output and the inverting output of the high-speed comparator are respectively connected to the differential clock terminals ~CLK and CLK of the D flip-flop, and the output of the D flip-flop is used to output a pulse signal.

[0056] The working process of the above-mentioned upconversion single-photon detector is as follows: After the avalanche photodiode in the detection circuit detects a photon, it generates an action signal. The action signal enters the high-speed comparator. When the action signal is lower than the discrimination level, the positive output terminal of the high-speed comparator generates a negative pulse signal. At the same time, the inverting output terminal of the high-speed comparator generates a positive pulse signal. Therefore, after the clock input terminal of the D flip-flop detects the rising edge signal, it generates a pulse signal at the output terminal. The pulse signal flows to the counting output module, the active quenching module, and the delay chip. After receiving the pulse signal, the counting output module outputs a counting pulse. After receiving the pulse signal, the active quenching module raises the anode potential of the avalanche photodiode to quench the avalanche effect. After the delay chip 6 performs the delay, it changes the value of the quenching resistor through the fast recovery module to lower the anode potential of the avalanche photodiode, so that the avalanche photodiode enters the detection waiting state of the next cycle.

[0057] like Figure 4 The diagram shown is a connection schematic of a controller and a single-photon detection component provided in this application. The controller includes an ADC circuit, an FPGA circuit, and a DAC circuit, as well as a temperature acquisition module and a temperature regulation module. The input terminal of the temperature acquisition module is connected to an avalanche photodiode to acquire the current temperature of the avalanche photodiode. The output terminal of the temperature acquisition module is connected to the ADC circuit to transmit the current temperature to the FPGA circuit. The input terminal of the temperature regulation module is connected to the FPGA circuit through the DAC circuit. The output terminal of the temperature regulation module is connected to a second temperature control device for regulating the temperature of the avalanche photodiode. The FPGA circuit controls the second temperature control device according to the current temperature to achieve temperature control of the avalanche photodiode and improve system stability.

[0058] In another embodiment, such as Figure 4 As shown, the controller also includes a voltage regulation module and a filter module. The input of the voltage regulation module is connected to the FPGA circuit through a DAC circuit, and the output of the voltage regulation module is connected to the second end of the quenching resistor. The filter module is set between the voltage regulation module and the quenching resistor to achieve precise control of the quenching resistor.

[0059] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An upconversion single-photon detector, characterized in that, Includes a single-photon detection component, a power stabilization component, and a controller for connecting the output of the frequency up-conversion waveguide; The single-photon detection component includes a detection circuit, which is used to collect the optical signal output from the output terminal of the frequency up-conversion waveguide and convert the optical signal into a detection signal and send it to the controller. The power stabilization component includes a beam splitter, a first photodiode, a temperature control device, and an operational amplifier circuit. The input terminal of the beam splitter is used to connect to a pump laser, the first output terminal of the beam splitter is used to connect to the frequency up-conversion waveguide, and the second output terminal of the beam splitter is connected to the photosensitive part of the first photodiode, so as to adjust the current passing through the first photodiode according to the light from the second output terminal of the beam splitter. The first photodiode is disposed in the temperature control device. The operational amplifier circuit is connected to the first photodiode for sampling. The output terminal of the operational amplifier circuit is connected to the controller to collect the current passing through the first photodiode and convert the current into a voltage signal to feed the voltage signal back to the controller. The controller is used to control the pump laser based on the detection signal and the voltage signal.

2. The upconversion single-photon detector according to claim 1, characterized in that, The temperature control device includes a temperature sensor and a first temperature control device. The first temperature control device is equipped with the first photodiode to control the ambient temperature of the first photodiode. The temperature sensor is located around the first photodiode to collect the ambient temperature of the first photodiode.

3. The upconversion single-photon detector according to claim 2, characterized in that, The first temperature control device includes at least two copper plates, one of which is provided with a first semiconductor cooling chip, and the first photodiode is disposed on the copper plate provided with the first semiconductor cooling chip, and the first photodiode is covered by another copper plate.

4. The upconversion single-photon detector according to claim 3, characterized in that, Each thermoelectric cooler is connected to the controller to control the temperature of the temperature control device according to the controller's control instructions. The temperature sensor is connected to the controller to send the collected temperature to the controller.

5. The upconversion single-photon detector according to claim 1, characterized in that, It also includes a sampling circuit, which uses a shielded twisted-pair cable, and the operational amplifier circuit is connected to the first photodiode through the sampling circuit.

6. The upconversion single-photon detector according to claim 1, characterized in that, The detection circuit includes a detection line, a comparator, a flip-flop, a counting output module, an active quenching module, a delay chip, and a fast recovery module; The detection circuit includes a silicon avalanche photodiode, a sampling resistor, and a quenching resistor connected in series. One end of the sampling resistor is connected to the power supply, and the other end of the sampling resistor is connected to the cathode of the avalanche photodiode. The cathode of the avalanche photodiode is connected to the input of the comparator. The output of the comparator is connected to the input of the flip-flop, the output of the flip-flop is connected to the input of the counting output module, the output of the flip-flop is connected to the input of the active quenching module, the output of the active quenching module is connected to the anode of the avalanche photodiode, the output of the flip-flop is connected to the input of the delay chip, the output of the delay chip is connected to the input of the fast recovery module, the output of the fast recovery module is connected to the common terminal of the quenching resistor, and the first end of the quenching resistor is connected to the anode of the avalanche photodiode.

7. The upconversion single-photon detector according to claim 6, characterized in that, The controller includes an ADC circuit, an FPGA circuit, and a DAC circuit. One end of the ADC circuit is connected to one end of the FPGA circuit, and the other end of the ADC circuit is connected to the output of the operational amplifier circuit. The other end of the FPGA circuit is connected to one end of the DAC circuit, and the other end of the DAC circuit is connected to the pump laser and the temperature control device.

8. The upconversion single-photon detector according to claim 7, characterized in that, The controller also includes a temperature acquisition module and a temperature regulation module; The input terminal of the temperature acquisition module is connected to the avalanche photodiode to acquire the current temperature of the avalanche photodiode, and the output terminal of the temperature acquisition module is connected to the ADC circuit to transmit the current temperature to the FPGA circuit. The input terminal of the temperature regulation module is connected to the FPGA circuit through the DAC circuit, and the output terminal of the temperature regulation module is connected to a second temperature control device for regulating the temperature of the avalanche photodiode. The FPGA circuit is used to control the second temperature control device according to the current temperature.

9. The upconversion single-photon detector according to claim 8, characterized in that, The controller further includes a voltage regulation module and a filtering module. The input terminal of the voltage regulation module is connected to the FPGA circuit through the DAC circuit, and the output terminal of the voltage regulation module is connected to the second terminal of the quenching resistor. The filtering module is disposed between the voltage regulation module and the quenching resistor.

10. An upconversion single-photon detection system, characterized in that, The upconversion single-photon detection system includes a host computer, a seed source, a pump laser, a frequency upconversion waveguide, and an upconversion single-photon detector as described in any one of claims 1 to 9. The seed source is connected to the pump laser, the pump laser is connected to the frequency upconversion waveguide through a beam splitter in the upconversion single-photon detector, the frequency upconversion waveguide is connected to the single-photon detection component in the upconversion single-photon detector, and the host computer is connected to the controller of the upconversion single-photon detector.

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