Gated single-photon detector peak noise suppression device and method

Abstract

The invention discloses a device and a method for suppressing peak noise of a gated single-photon detector, and belongs to the field of big data. The device comprises a negative gate pulse signal module, a first peak noise extraction module, a second peak noise extraction module and a multistage converter module, wherein the output end of the negative gate pulse signal module is connected with the input end of the first peak noise extraction module and the input end of the second peak noise extraction module; the input end of the multi-stage converter module is connected with the output end of the first peak noise extraction module and the output end of the second peak noise extraction module. According to the invention, the peak noise of the APD can be suppressed, the dark counting rate and the post-pulse probability are reduced, the circuit design is simplified, and the reliability and the stability of the gated single-photon detector are improved.

Description

Technical Field

[0001] The invention belongs to the field of signal processing, and in particular relates to a device and method for suppressing peak noise of a gated single-photon detector. Background Art

[0002] Gated single-photon detectors can be used in pulsed light detection systems where the arrival time of photons is determined. They are one of the core devices of systems such as quantum key distribution (QKD). The single-photon detector works in gated mode, and the gate pulse signal is loaded on one end of the avalanche diode (APD) and transmitted through the APD. Due to the differential effect of the APD junction capacitance, a large spike noise will be generated after the gate pulse is transmitted through the APD, which will annihilate the avalanche signal. Therefore, only by eliminating the spike noise of the APD can the avalanche signal be effectively extracted, and then identified and output. Therefore, the detection efficiency, dark count rate, and after-pulse probability of the gated single-photon detector depend on the performance of the APD avalanche signal processing circuit, that is, the ability of the processing circuit to suppress spike noise.

[0003] Low-pass filtering is one of the technical means to suppress spike noise in gated single-photon detectors, that is, to suppress or filter out spike noise through a low-pass filter. Since the cutoff frequency of the low-pass filter is slightly lower than the frequency of the gate pulse signal, spike noise can be suppressed, but the suppression effect is limited. If the cutoff frequency of the low-pass filter is much lower than the frequency of the gate pulse signal, it will affect the characteristics of the avalanche signal, and thus affect the detection efficiency of the detector.

[0004] Capacitor balance elimination is also one of the technical means to suppress spike noise in gated single-photon detectors, that is, a capacitor or diode similar to the APD junction capacitance is used to generate spike noise similar to that generated by the APD, and then a differential amplifier is used to perform differential operations to cancel out the common-mode signals, thereby achieving the purpose of spike noise suppression. The available patents and literature have corresponding introductions to this method, but the specific implementation process is relatively cumbersome, the circuit design is relatively complex, and the final implementation effect is not good, resulting in average dark count rate and after-pulse probability characteristics of the single-photon detector. Summary of the invention

[0005] The present invention aims to overcome the deficiencies of the prior art and proposes a gated single-photon detector spike noise suppression device and method to suppress the spike noise of APD, reduce the dark count rate and after-pulse probability, simplify the circuit design, and improve the reliability and stability of the gated single-photon detector.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a gated single-photon detector spike noise suppression device, the device includes a negative gate pulse signal module, a first spike noise extraction module, a second spike noise extraction module, and a multi-stage converter module, wherein: the output end of the negative gate pulse signal module is respectively connected to the input end of the first spike noise extraction module and the second spike noise extraction module; the input end of the multi-stage converter module is respectively connected to the output end of the first spike noise extraction module and the second spike noise extraction module.

[0007] Preferably, the device further comprises an input impedance matching circuit, and the input impedance matching circuit comprises a resistor R2, wherein: one end of the resistor R2 is grounded, and the other end is connected to the output end of the negative gate pulse signal module.

[0008] Preferably, the first spike noise extraction module includes an avalanche diode APD, resistors R1 and R3, capacitors C1 and C3, and a physical delay line DL1, wherein: the anode of the avalanche diode APD is the input end of the first spike noise extraction module, and the reverse bias voltage HV is loaded on the cathode of the avalanche diode APD through the resistor R1; one end of the capacitor C1 is connected to the cathode of the avalanche diode APD, and the other end of the capacitor C1 is connected to the M1 end of the physical delay line DL1; one end of the capacitor C3 is connected to the M2 end of the physical delay line DL1, and the other end of the capacitor C3 is grounded through the resistor R3 and the lead terminal is used as the output end of the first spike noise extraction module.

[0009] Preferably, the second spike noise extraction module includes high-frequency capacitive devices Ct1 and Ct2, a resistor R4, capacitors C2 and C4, and a physical delay line DL2, wherein: the input end of the second spike noise extraction module is connected to the N1 end of the physical delay line DL2 through the high-frequency capacitive device Ct1, the high-frequency capacitive device Ct2, and the capacitor C2 which are connected in series in sequence; one end of the capacitor C4 is connected to the N2 end of the physical delay line DL2, and the other end of the capacitor C4 is grounded through the resistor R4 and the lead terminal is used as the output end of the second spike noise extraction module.

[0010] Preferably, the high-frequency capacitive devices Ct1 and Ct2 are both mechanically adjustable high-frequency capacitive devices, which can generate spike noises of different amplitudes by adjusting their capacitance values.

[0011] Preferably, the multi-stage converter module includes a high-speed converter 1 and a high-speed converter 2, which are connected in series, wherein: the input end I1 of the high-speed converter 1 is connected to the output end of the first spike noise extraction module; the input end I2 of the high-speed converter 1 is connected to the output end of the second spike noise extraction module; the output end O1 of the high-speed converter 1 is connected to the input end I1 of the high-speed converter 2; the output end O2 of the high-speed converter 1 is connected to the input end I2 of the high-speed converter 2; the output end O1 of the high-speed converter 2 is grounded, and the output end O2 of the high-speed converter 2 serves as the output end of the multi-stage converter module.

[0012] Preferably, the amplitude value after superposition of the negative gate pulse signal GATE output by the negative gate pulse signal module and the reverse bias voltage HV is higher than the avalanche breakdown voltage Vbr of the avalanche diode APD.

[0013] Preferably, the impedance matching circuit is used to achieve 50 ohm impedance matching on the output of the negative gate pulse signal generating circuit.

[0014] Preferably, the high-speed converter 1 and the high-speed converter 2 are both 1:1 transmission line converters with 50 ohm impedance matching properties and are passive devices.

[0015] At the same time, the present invention also proposes a method for suppressing spike noise of a gated single-photon detector according to the above device, and the method comprises the following steps:

[0016] S1: According to the schematic diagram, correctly solder the corresponding circuit board;

[0017] S2: Connect capacitor C3 and disconnect capacitor C4, that is, turn on the first peak noise extraction module and disconnect the second peak noise extraction module;

[0018] S3: The circuit board is powered on, and the negative gate pulse signal module generates a negative gate pulse signal;

[0019] S4: connecting the output end of the multi-stage converter module to an oscilloscope to record the amplitude information and position information of the first peak noise;

[0020] S5: the negative gate pulse signal module stops generating the negative gate pulse signal, and the circuit board is powered off;

[0021] S6: Connect the capacitor C4 and disconnect the capacitor C3, that is, turn on the second peak noise extraction module and disconnect the first peak noise extraction module;

[0022] S7: The circuit board is powered on, and the negative gate pulse signal module generates a negative gate pulse signal;

[0023] S8: connecting the output end of the multi-stage converter module to an oscilloscope to record the amplitude information and position information of the second peak noise;

[0024] S9: referring to the position information of the first spike noise in step S4, adjusting the length of the physical delay line DL2 between port N1 and port N2 so that the position information of the second spike noise recorded in step S8 is consistent with the position information recorded in step S4;

[0025] S10: referring to the amplitude information of the first peak noise in step S4, adjusting the high-frequency capacitive components Ct1 and Ct2 so that the amplitude information of the second peak noise recorded in step S8 is consistent with the amplitude information recorded in step S4;

[0026] S11: the negative gate pulse signal module stops generating the negative gate pulse signal, and the circuit board is powered off;

[0027] S12: reconnecting the capacitor C3, that is, both the first spike noise extraction module and the second spike noise extraction module are turned on;

[0028] S13: The circuit board is powered on, and the negative gate pulse signal module generates a negative gate pulse signal;

[0029] S14: Connect the output end of the multi-stage converter module to an oscilloscope, and observe that the peak noise is effectively suppressed.

[0030] The technical effects of the present invention are:

[0031] 1. Use an extremely narrow negative gate pulse signal to load the anode of the APD through DC coupling to achieve APD Geiger mode operation, and perform 50 ohm matching input at the input end.

[0032] 2. A mechanical high-frequency capacitive device is used to generate peak noise with adjustable amplitude, which has a stable mechanical structure and high reliability. Since there is no need to apply a bias high voltage to one end of the capacitive device, the corresponding design circuit is simplified.

[0033] 3. The physical delay lines DL1 and DL2 are passive devices with high stability. The high-speed converters 1 and 2 are passive devices of transmission lines and do not require power supply, thus avoiding the introduction of additional noise and further avoiding the influence of electronic noise.

[0034] 4. The present invention can suppress the spike noise of APD, reduce the dark count rate and after-pulse probability, simplify the circuit design, and improve the reliability and stability of the gated single-photon detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of a gate pulse realizing a Geiger mode according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of a spike noise suppression device according to an embodiment of the present invention;

[0037] Figure 3 FIG. 4 is a flow chart of a spike noise suppression method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following is a further detailed description of the specific implementation of the present invention through the description of the embodiments with reference to the accompanying drawings, with the purpose of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention and to facilitate its implementation. In order to make the technical solution of the present invention clearer, the present invention is explained through the following embodiments:

[0039] When the gated single photon detector is working, it is usually necessary to make the avalanche diode APD work in Geiger mode. Under normal circumstances, for any APD, its avalanche breakdown voltage Vbr at a specific temperature can be accurately measured. At this time, the APD can be made to work in Geiger mode by simply increasing the voltage loaded on both ends of the APD to exceed Vbr. Based on the above, the present invention introduces a method for realizing Geiger mode by gate pulse, that is, Figure 1 As shown, the amplitude value after the reverse bias voltage Vb loaded on the APD cathode and the extremely narrow gate pulse signal GATE loaded on the APD anode is superimposed is higher than the avalanche breakdown voltage Vbr, thereby realizing the Geiger mode. This method is applied in the gated single-photon detector of the present invention, which can effectively reduce the dark count rate and the after-pulse probability, and improve the detection efficiency. However, it is accompanied by greater spike noise. Therefore, the present invention further proposes a spike noise suppression device that can effectively suppress the spike noise of the APD and improve the reliability and stability of the gated single-photon detector.

[0040] A gated single photon detector spike noise suppression device, such as Figure 2 As shown, the device includes a negative gate pulse signal module, a first spike noise extraction module, a second spike noise extraction module, and a multi-stage converter module, wherein: the output end (A end) of the negative gate pulse signal module is respectively connected to the input ends of the first spike noise extraction module and the second spike noise extraction module; the input end of the multi-stage converter module is respectively connected to the output ends (B end) of the first spike noise extraction module and the second spike noise extraction module.

[0041] Specifically, the device also includes an input impedance matching circuit, and the input impedance matching circuit includes a resistor R2, wherein: one end of the resistor R2 is grounded, and the other end is connected to the output end of the negative gate pulse signal module. The negative gate pulse signal module is used to generate a negative gate pulse signal, and input the first spike noise extraction module and the second spike noise extraction module after DC coupling. In this embodiment, the input impedance matching circuit is used to achieve 50 ohm impedance matching for the output of the negative gate pulse signal module, that is, the resistor R2 can be set to 50 ohms and then grounded to achieve impedance matching. In this embodiment, the negative gate pulse signal module can be composed of components such as gate circuits and triggers, or it can be other highly integrated pulse signal generating devices. The specific circuits or devices are relatively common in the prior art, and the present invention will not be repeated here.

[0042] Specifically, the first spike noise extraction module of the present embodiment includes an avalanche diode APD, resistors R1 and R3, capacitors C1 and C3, and a physical delay line DL1, wherein: the anode of the avalanche diode APD is the input end of the first spike noise extraction module, and the reverse bias voltage HV is loaded on the cathode of the avalanche diode APD through the resistor R1; one end of the capacitor C1 is connected to the cathode of the avalanche diode APD, and the other end of the capacitor C1 is connected to the M1 end of the physical delay line DL1; one end of the capacitor C3 is connected to the M2 end of the physical delay line DL1, and the other end of the capacitor C3 is grounded through the resistor R3 and the lead terminal is used as the output end of the first spike noise extraction module. Preferably, in order to make the APD in Geiger mode, in the present embodiment, the amplitude value of the negative gate pulse signal GATE output by the negative gate pulse signal module and the reverse bias voltage HV after superposition needs to be higher than the avalanche breakdown voltage Vbr of the avalanche diode APD.

[0043] Specifically, the second peak noise extraction module of the present embodiment includes high-frequency capacitive devices Ct1 and Ct2, a resistor R4, capacitors C2 and C4, and a physical delay line DL2, wherein: the input end of the second peak noise extraction module is connected to the N1 end of the physical delay line DL2 through the high-frequency capacitive device Ct1, the high-frequency capacitive device Ct2, and the capacitor C2 connected in series in sequence; one end of the capacitor C4 is connected to the N2 end of the physical delay line DL2, and the other end of the capacitor C4 is grounded through the resistor R4 and the lead terminal is used as the output end of the second peak noise extraction module. In the present embodiment, the high-frequency capacitive devices Ct1 and Ct2 are both mechanically adjustable high-frequency capacitive devices, which can generate peak noises of different amplitudes by adjusting their capacitance values. The mechanical structure is stable and the reliability is high. At the same time, since there is no need to apply a bias high voltage to one end of the capacitive device, the corresponding design circuit is simplified. In addition, the physical delay line DL1 and the physical delay line DL2 used in the present embodiment are both passive devices, which have the advantage of high stability.

[0044] Specifically, the multi-stage converter module of this embodiment includes a high-speed converter 1 and a high-speed converter 2, and the high-speed converter 1 and the high-speed converter 2 are connected in series, wherein: the input terminal I1 of the high-speed converter 1 is connected to the output terminal of the first spike noise extraction module; the input terminal I2 of the high-speed converter 1 is connected to the output terminal of the second spike noise extraction module; the output terminal O1 of the high-speed converter 1 is connected to the input terminal I1 of the high-speed converter 2; the output terminal O2 of the high-speed converter 1 is connected to the input terminal I2 of the high-speed converter 2; the output terminal O1 of the high-speed converter 2 is grounded, and the output terminal O2 of the high-speed converter 2 serves as the output terminal of the multi-stage converter module. In this embodiment, the high-speed converter 1 and the high-speed converter 2 are both 1:1 transmission line converters with 50 ohm impedance matching properties, which are passive devices and do not require power supply, thereby avoiding the introduction of additional noise, and further avoiding the influence of electronic noise.

[0045] At the same time, the present invention also proposes a method for suppressing peak noise of a gated single-photon detector based on the above device, such as Figure 3 As shown, the method comprises the following steps:

[0046] S1: According to the schematic diagram, correctly solder the corresponding circuit board to ensure that the circuit board is soldered properly without any cold solder joints and the solder joints are smooth and free of burrs, thus ensuring the integrity of the spike noise;

[0047] S2: connect capacitor C3 and disconnect capacitor C4, that is, turn on the first peak noise extraction module, only measure the peak noise information of the path, and disconnect the second peak noise extraction module;

[0048] S3: The circuit board is powered on, the negative gate pulse signal module (A terminal) generates a negative gate pulse signal and loads it on the anode of the APD. The spike noise is extracted at the cathode of the APD and reaches the output terminal (B terminal) of the multi-stage converter module after transmission.

[0049] S4: Connect the output end of the multi-stage converter module to an oscilloscope, observe the amplitude information and position information of the first peak noise, and mark and record them through the oscilloscope coordinate ruler;

[0050] S5: The negative gate pulse signal module stops generating negative gate pulse signals, and the circuit board is powered off;

[0051] S6: Connect the capacitor C4 and disconnect the capacitor C3, that is, turn on the second peak noise extraction module to measure only the peak noise information of the path, and disconnect the first peak noise extraction module;

[0052] S7: The circuit board is powered on, the negative gate pulse signal module (A terminal) generates a negative gate pulse signal, which is loaded on the input terminal of the second spike noise extraction module and reaches the output terminal (B terminal) of the multi-stage converter module after transmission;

[0053] S8: Connect the output end of the multi-stage converter module to an oscilloscope, observe the amplitude information and position information of the second peak noise, mark and record it through the oscilloscope coordinate ruler, and compare it with the amplitude information and position information of the first peak noise recorded in step S4;

[0054] S9: referring to the position information of the first spike noise in step S4, adjusting the length of the physical delay line DL2 between port N1 and port N2, so that the position information of the second spike noise recorded in step S8 is consistent with the position information recorded in step S4, that is, the consistency of the spike noise position information is achieved, and the phase matching of the spike noise is completed;

[0055] S10: referring to the amplitude information of the first peak noise in step S4, adjusting the high-frequency capacitive components Ct1 and Ct2, so that the amplitude information of the second peak noise recorded in step S8 is consistent with the amplitude information recorded in step S4, that is, the peak noise amplitude information is consistent;

[0056] S11: The negative gate pulse signal module stops generating negative gate pulse signals, and the circuit board is powered off;

[0057] S12: reconnecting the capacitor C3, that is, both the first peak noise extraction module and the second peak noise extraction module are turned on, completing the balance of the two branches;

[0058] S13: The circuit board is powered on, and the negative gate pulse signal module generates a negative gate pulse signal;

[0059] S14: Connect the output end of the multi-stage converter module to an oscilloscope, and it can be observed that the spike noise is effectively suppressed. At this point, the gated single photon detector spike noise suppression operation is completed.

[0060] In view of the shortcomings of the current gated single-photon detector spike noise suppression technology, the present invention provides a gated single-photon detector spike noise suppression device and method, the present invention can not only suppress the APD spike noise, reduce the dark count rate and after-pulse probability, but also simplify the circuit design, and improve the reliability and stability of the gated single-photon detector.

[0061] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A gated single-photon detector spike noise suppression device, characterized in that: The device includes a negative gate pulse signal module, a first spike noise extraction module, a second spike noise extraction module, and a multi-stage converter module, wherein: the output end of the negative gate pulse signal module is respectively connected to the input ends of the first spike noise extraction module and the second spike noise extraction module; the input end of the multi-stage converter module is respectively connected to the output ends of the first spike noise extraction module and the second spike noise extraction module.

2. The gated single photon detector spike noise suppression device according to claim 1, characterized in that: The device further comprises an input impedance matching circuit, wherein the input impedance matching circuit comprises a resistor R2, wherein: one end of the resistor R2 is grounded, and the other end is connected to the output end of the negative gate pulse signal module.

3. The gated single photon detector spike noise suppression device according to claim 1, characterized in that: The first spike noise extraction module includes an avalanche diode APD, resistors R1 and R3, capacitors C1 and C3, and a physical delay line DL1, wherein: the anode of the avalanche diode APD is the input end of the first spike noise extraction module, and the reverse bias voltage HV is loaded on the cathode of the avalanche diode APD through the resistor R1; one end of the capacitor C1 is connected to the cathode of the avalanche diode APD, and the other end of the capacitor C1 is connected to the M1 end of the physical delay line DL1; one end of the capacitor C3 is connected to the M2 end of the physical delay line DL1, and the other end of the capacitor C3 is grounded through the resistor R3 and the lead terminal is used as the output end of the first spike noise extraction module.

4. The gated single photon detector spike noise suppression device according to claim 1, characterized in that: The second spike noise extraction module includes high-frequency capacitive devices Ct1 and Ct2, a resistor R4, capacitors C2 and C4, and a physical delay line DL2, wherein: the input end of the second spike noise extraction module is connected to the N1 end of the physical delay line DL2 through the high-frequency capacitive device Ct1, the high-frequency capacitive device Ct2, and the capacitor C2 connected in series in sequence; one end of the capacitor C4 is connected to the N2 end of the physical delay line DL2, and the other end of the capacitor C4 is grounded through the resistor R4 and the lead terminal is used as the output end of the second spike noise extraction module.

5. The gated single photon detector spike noise suppression device according to claim 4, characterized in that: The high-frequency capacitive devices Ct1 and Ct2 are both mechanically adjustable high-frequency capacitive devices, which can generate peak noises of different amplitudes by adjusting their capacitance values.

6. The gated single photon detector spike noise suppression device according to claim 1, characterized in that: The multi-stage converter module includes a high-speed converter 1 and a high-speed converter 2, which are connected in series, wherein: the input end I1 of the high-speed converter 1 is connected to the output end of the first spike noise extraction module; the input end I2 of the high-speed converter 1 is connected to the output end of the second spike noise extraction module; the output end O1 of the high-speed converter 1 is connected to the input end I1 of the high-speed converter 2; the output end O2 of the high-speed converter 1 is connected to the input end I2 of the high-speed converter 2; the output end O1 of the high-speed converter 2 is grounded, and the output end O2 of the high-speed converter 2 serves as the output end of the multi-stage converter module.

7. The gated single photon detector spike noise suppression device according to claim 3, characterized in that: The amplitude value of the negative gate pulse signal GATE output by the negative gate pulse signal module and the reverse bias voltage HV after superposition is higher than the avalanche breakdown voltage Vbr of the avalanche diode APD.

8. The gated single photon detector spike noise suppression device according to claim 2, characterized in that: The input impedance matching circuit is used to achieve 50 ohm impedance matching on the output of the negative gate pulse signal module.

9. The gated single photon detector spike noise suppression device according to claim 6, characterized in that: The high-speed converter 1 and the high-speed converter 2 are both 1:1 transmission line converters with 50 ohm impedance matching properties and are passive devices.

10. A method for suppressing peak noise of a gated single-photon detector according to the device of any one of claims 1 to 9, characterized in that: The method comprises the following steps: S1: According to the schematic diagram, correctly solder the corresponding circuit board; S2: Connect capacitor C3 and disconnect capacitor C4, that is, turn on the first peak noise extraction module and disconnect the second peak noise extraction module; S3: The circuit board is powered on, and the negative gate pulse signal module generates a negative gate pulse signal; S4: connecting the output end of the multi-stage converter module to an oscilloscope to record the amplitude information and position information of the first peak noise; S5: the negative gate pulse signal module stops generating the negative gate pulse signal, and the circuit board is powered off; S6: Connect the capacitor C4 and disconnect the capacitor C3, that is, turn on the second peak noise extraction module and disconnect the first peak noise extraction module; S7: The circuit board is powered on, and the negative gate pulse signal module generates a negative gate pulse signal; S8: connecting the output end of the multi-stage converter module to an oscilloscope to record the amplitude information and position information of the second peak noise; S9: referring to the position information of the first spike noise in step S4, adjusting the length of the physical delay line DL2 between port N1 and port N2 so that the position information of the second spike noise recorded in step S8 is consistent with the position information recorded in step S4; S10: referring to the amplitude information of the first peak noise in step S4, adjusting the high-frequency capacitive components Ct1 and Ct2 so that the amplitude information of the second peak noise recorded in step S8 is consistent with the amplitude information recorded in step S4; S11: the negative gate pulse signal module stops generating the negative gate pulse signal, and the circuit board is powered off; S12: reconnecting the capacitor C3, that is, both the first spike noise extraction module and the second spike noise extraction module are turned on; S13: The circuit board is powered on, and the negative gate pulse signal module generates a negative gate pulse signal; S14: Connect the output end of the multi-stage converter module to an oscilloscope, and observe that the peak noise is effectively suppressed.

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