System and method for generating gating signal of single-photon detector

Abstract

The invention provides a single-photon detector gating signal generation system and generation method. The system comprises a bias voltage source; the gating circuit is provided with a first sine branch and a second sine branch, the first sine branch is configured to output a first sine voltage signal, and the second sine branch is configured to output a second sine voltage signal; the frequency of the first sinusoidal voltage signal is greater than that of the second sinusoidal voltage signal; the second sinusoidal voltage signal, the first sinusoidal voltage signal and the bias voltage signal are matched to generate a gating signal acting on the avalanche photodiode; based on the period of the first sinusoidal voltage signal, the gating signal has an amplitude greater than a preset value in a continuous first number of periods, and the gating signal does not have an amplitude greater than the preset value in a subsequent continuous second number of periods. The generated gating signal can accelerate the carrier removal process from the physical mechanism level, the post-pulse probability is suppressed, the required dead time is effectively shortened, and the data rate of the detector is further improved.

Description

Technical Field

[0001] This invention relates to the field of optical detection, and in particular to a single-photon detector gating signal generation system and method. Background Technology

[0002] A single-photon detector is an ultrasensitive photoelectric detection device capable of detecting the energy of a single photon. It is a core component in quantum technology, precision measurement, and ultra-weak light detection. In current high-speed single-photon detection systems, sinusoidal gating is typically employed to reduce dark count rate and afterpulse rate. Figure 1 This is a schematic diagram of a high-frequency sinusoidal gating signal in the prior art, such as... Figure 1 As shown, the DC bias voltage V dc Set at slightly below the breakdown voltage V of the avalanche photodiode (APD) br The peak value of the sinusoidal gated signal within one cycle causes the instantaneous total voltage to be slightly higher than V. br This puts APD in the avalanche window T. W Other cycle times are lower than the breakdown voltage V. br Within the avalanche window, if a photon enters, it will trigger the APD to generate an avalanche pulse signal. In practice, to suppress afterpulses, a dead time T is set for a period of time after each avalanche. d During this period, the pulse signal output is discarded by the digital circuitry. However, within the dead time, the gating signal continues to operate, and its peak value periodically exceeds the breakdown voltage. Carriers may still trigger multiple afterpulses, increasing the overall afterpulse probability and the required dead time. The existence of the dead time severely limits the effective data rate of single-photon detectors. Summary of the Invention

[0003] In view of the above problems, the present invention is proposed to provide a single-photon detector gating signal generation system and method that overcomes or at least partially solves the above problems, effectively alleviates multi-stage afterpulse, thereby shortening the required dead time and improving the single-photon detector data rate.

[0004] Specifically, the present invention provides a single-photon detector gating signal generation system, comprising:

[0005] A bias voltage source is used to connect to the cathode of an avalanche photodiode and is configured to output a bias voltage signal.

[0006] A gated circuit having a first sinusoidal branch and a second sinusoidal branch, wherein the first sinusoidal branch is configured to output a first sinusoidal voltage signal and the second sinusoidal branch is configured to output a second sinusoidal voltage signal;

[0007] The frequency of the first sinusoidal voltage signal is greater than the frequency of the second sinusoidal voltage signal;

[0008] The second sinusoidal voltage signal, the first sinusoidal voltage signal, and the bias voltage signal generate a gating signal acting on the cathode of the avalanche photodiode; based on the period of the first sinusoidal voltage signal, the gating signal has an amplitude greater than a preset value within one period or within a first consecutive number of periods, and the gating signal does not have an amplitude greater than the preset value within the next second consecutive number of periods.

[0009] Optionally, the gated circuit further includes a mixer;

[0010] Both the first sine branch and the second sine branch are connected to the input terminal of the mixer, and the output terminal of the mixer is connected to the cathode of the avalanche photodiode.

[0011] The second sinusoidal voltage signal is a modulation signal used to adjust the amplitude of the first sinusoidal voltage signal.

[0012] Optionally, the first sinusoidal voltage signal is A1sin2πf g t, A1 is the amplitude of the first sinusoidal voltage signal, f g The frequency of the first sinusoidal voltage signal is denoted as t, and t is a time parameter.

[0013] The second sinusoidal voltage signal is A2sin2π(f g / N)t, A2 is the amplitude of the second sinusoidal voltage signal, N is the ratio between the frequency of the first sinusoidal voltage signal and the frequency of the second sinusoidal voltage signal, and N is an odd number.

[0014] Optionally, the gate circuit further includes an adder;

[0015] Both the first sine branch and the second sine branch are connected to the input terminal of the adder, and the output terminal of the adder is connected to the cathode of the avalanche photodiode.

[0016] Optionally, the first sinusoidal voltage signal is: A1sin2πf g t, A1 is the amplitude of the first sinusoidal voltage signal, f g The frequency of the first sinusoidal voltage signal is denoted as t, and t is a time parameter.

[0017] The second sinusoidal voltage signal is A2sin2πf m t, A2 is the amplitude of the first sinusoidal voltage signal and is greater than A1, f m f is the frequency of the second sinusoidal voltage signal, t is the time parameter; g = (1+4k)*f m k is a positive integer.

[0018] Optionally, the gating circuit further includes a signal shaping circuit, an amplifier, and a capacitor;

[0019] The gating signal is connected to the cathode of the avalanche photodiode in sequence through the signal shaping circuit, the amplifier, and the capacitor.

[0020] Optionally, the frequency of the first sine branch can be adjusted, and the frequency of the second sine branch can be adjusted.

[0021] Optionally, the bias voltage signal is less than the breakdown voltage of the avalanche photodiode;

[0022] The preset value is equal to the breakdown voltage.

[0023] This invention also provides a method for generating a single-photon detector gating signal, which utilizes any of the above-mentioned single-photon detector gating signal generation systems to generate a gating signal acting on the cathode of an avalanche photodiode; comprising:

[0024] The bias voltage signal is generated using the bias voltage source;

[0025] The first sinusoidal voltage signal is generated using the first sinusoidal branch.

[0026] The second sinusoidal voltage signal is generated using the second sinusoidal branch.

[0027] The second sinusoidal voltage signal, the first sinusoidal voltage signal, and the bias voltage signal are used to generate the gate signal.

[0028] In the single-photon detector gating signal generation system and method of the present invention, due to the presence of a first sinusoidal branch and a second sinusoidal branch, a special signal is generated by the interaction of the first and second sinusoidal branches and superimposed with a bias voltage signal. This ensures that the gating signal does not have an amplitude greater than the breakdown voltage for a second number of consecutive cycles. Thus, within the dead time, the chance of carrier-triggered avalanche is reduced, and the generation of afterpulses is minimized, thereby lowering the probability of afterpulses. In other words, the carrier clearance process is accelerated and the probability of afterpulses is suppressed from a physical mechanism perspective. Because of the reduction in afterpulses, the required dead time is shortened, thereby increasing the data rate of the single-photon detector.

[0029] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0030] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0031] Figure 1 This is a schematic diagram of a high-frequency sinusoidal gating signal in the prior art;

[0032] Figure 2 This is a schematic circuit diagram of a single-photon detector gating signal generation system according to an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of a gate signal generation system for a single-photon detector according to an embodiment of the present invention;

[0034] Figure 4 This is a schematic circuit diagram of a single-photon detector gating signal generation system according to an embodiment of the present invention;

[0035] Figure 5 This is a schematic partial circuit diagram of a single-photon detector gating signal generation system according to an embodiment of the present invention;

[0036] Figure 6 This is a schematic diagram of a gate signal generation system for a single-photon detector according to an embodiment of the present invention. Detailed Implementation

[0037] The following reference Figures 2 to 6 This invention describes a single-photon detector gating signal generation system and method according to embodiments of the present invention. In this description, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature, that is, include one or more of that feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. When a feature "includes or contains" one or more of the features it encompasses, unless otherwise specifically described, this indicates that other features are not excluded and may be further included.

[0038] Unless otherwise expressly specified and limited, the terms "set up," "install," "connect," "link," "fix," and "couple" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art should be able to understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] Furthermore, in the description of this embodiment, "above" or "below" the second feature can include direct contact between the first and second features, or it can include contact between the first and second features through another feature between them. That is, in the description of this embodiment, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "below" of the second feature can mean the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] In the description of this embodiment, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] Figure 2 This is a schematic circuit diagram of a single-photon detector gating signal generation system according to an embodiment of the present invention, such as... Figure 2 As shown and referenced Figures 3 to 6 This invention provides a single-photon detector gating signal generation system, which includes a bias voltage source 20 and a gating circuit. An avalanche photodiode 10 is a high-performance photodetector that utilizes the avalanche multiplication effect to convert optical signals into electrical signals and internally amplifies them. The bias voltage source 20 is connected to the cathode of the avalanche photodiode 10 to provide a bias voltage signal. The gating circuit has a first sinusoidal branch 31 and a second sinusoidal branch 32. The first sinusoidal branch 31 is configured to output a first sinusoidal voltage signal, and the second sinusoidal branch 32 is configured to output a second sinusoidal voltage signal.

[0042] The frequency of the first sinusoidal voltage signal is greater than the frequency of the second sinusoidal voltage signal. The second sinusoidal voltage signal and the first sinusoidal voltage signal are combined and superimposed with a bias voltage signal to generate a gating signal acting on the cathode of the avalanche photodiode 10. Based on the period of the first sinusoidal voltage signal, the gating signal has an amplitude greater than a preset value within one period or for a consecutive first number of periods, and does not have an amplitude greater than the preset value for the following consecutive second number of periods.

[0043] The bias voltage provided by bias voltage source 20 is less than the breakdown voltage of avalanche photodiode 10. The preset value is equal to the breakdown voltage.

[0044] In the single-photon detector gating signal generation system of this invention, such as Figure 2 and Figure 3 As shown, during operation, the first sinusoidal branch 31 and the second sinusoidal branch 32 operate simultaneously, providing a special signal that, in conjunction with the bias voltage signal provided by the bias voltage source 20, generates a control voltage signal acting on the avalanche photodiode 10. Based on the period of the first sinusoidal voltage signal, within a first consecutive number of periods, the maximum control voltage can be greater than the breakdown voltage, and within the following second consecutive number of periods, the maximum control voltage is not greater than the breakdown voltage. Thus, since the maximum control voltage is not greater than the breakdown voltage, no afterpulse is generated during this period, thereby accelerating the carrier removal process from a physical mechanism perspective and suppressing the probability of afterpulse. Furthermore, the number of periods where the maximum control voltage can be greater than the breakdown voltage is relatively small, resulting in fewer periods requiring shielding or being discarded within the dead time, facilitating control. Preferably, there is only one period where the maximum control voltage can be greater than the breakdown voltage.

[0045] In other words, in the single-photon detector gating signal generation system of this embodiment, due to the presence of a first sinusoidal branch 31 and a second sinusoidal branch 32, a special signal is generated by the interaction of the first sinusoidal branch 31 and the second sinusoidal branch 32 and superimposed with a bias voltage signal. This ensures that the gating signal does not have an amplitude greater than the preset value for a second number of consecutive cycles. Thus, within the dead time, the chance of carrier-triggered avalanche is reduced, and the generation of afterpulses is prevented as much as possible, reducing the probability of afterpulses. That is, from a physical mechanism perspective, the carrier removal process is accelerated, and the probability of afterpulses is suppressed. Because of the reduction in afterpulses, the required dead time is shortened, thereby increasing the data rate of the single-photon detector.

[0046] In some embodiments of the present invention, such as Figure 2 and Figure 3As shown, the gating circuit also includes a mixer 33. The first sinusoidal branch 31 and the second sinusoidal branch 32 are both connected to the input terminal of the mixer 33, and the output terminal of the mixer 33 is connected to the cathode of the avalanche photodiode 10. The second sinusoidal voltage signal is a modulation signal used to adjust the amplitude of the first sinusoidal voltage signal. In this embodiment of the invention, using a low-frequency second sinusoidal voltage signal to perform low-frequency modulation on the high-frequency first sinusoidal voltage signal simplifies the circuit and ensures the stability of the gating signal.

[0047] In some embodiments of the present invention, the first sinusoidal voltage signal is A1sin2πf g t, A1 is the amplitude of the first sinusoidal voltage signal, f g Let be the frequency of the first sinusoidal voltage signal, and t be the time parameter. The second sinusoidal voltage signal is A²sin²π(f...). g / N)t, A2 is the amplitude of the second sinusoidal voltage signal. The signal after the first and second sinusoidal voltage signals are combined is A1A2sin2π(f g / N)t×sin2πf g t. N is the ratio between the frequency of the first sinusoidal voltage signal and the frequency of the second sinusoidal voltage signal, and N is an odd number.

[0048] In this embodiment of the invention, the amplitude of the first sinusoidal voltage signal, the frequency of the first sinusoidal voltage signal, the amplitude of the second sinusoidal voltage signal, and the ratio between the frequency of the first sinusoidal voltage signal and the frequency of the second sinusoidal voltage signal can all be set as needed. Preferably, the ratio between the frequency of the first sinusoidal voltage signal and the frequency of the second sinusoidal voltage signal is an odd number, such that the period of the second sinusoidal voltage signal is an integer multiple of the period of the first sinusoidal voltage signal, and the time when the maximum value of the second sinusoidal voltage signal occurs coincides with the time when the maximum value of the first sinusoidal voltage signal occurs.

[0049] In other embodiments of the invention, such as Figures 4 to 6 As shown, the gated circuit also includes an adder 37. The first sine branch 31 and the second sine branch 32 are both connected to the input of the adder 37, and the output of the adder 37 is connected to the cathode of the avalanche photodiode 10. By setting the adder 37, the first quantity can be significantly lower than the second quantity, which is beneficial for suppressing afterpulses and designing a shorter dead time.

[0050] In some embodiments of the present invention, such as Figure 5 As shown, the first sinusoidal voltage signal is A1sin2πf g t, A1 is the amplitude of the first sinusoidal voltage signal, f g Let be the frequency of the first sinusoidal voltage signal, and t be the time parameter. The second sinusoidal voltage signal is A²sin²πf. mt, A2 is the amplitude of the first sinusoidal voltage signal and is greater than A1, f m f is the frequency of the second sinusoidal voltage signal, and t is the time parameter. g = (1+4k)*f m k is a positive integer. The signal resulting from the combination of the first and second sinusoidal voltage signals is: R f As feedback resistors, R1 is a resistor located between the first sine branch 31 and the input terminal of the adder 37, and R2 is a resistor located between the second sine branch 32 and the input terminal of the adder 37. Preferably, R1 = R2.

[0051] In some embodiments of the present invention, the frequency of the second sinusoidal branch 32 can be adjusted. By adjusting the frequency of the second sinusoidal branch 32, the values ​​of the first quantity, the second quantity, etc., can be changed, making it applicable to different detection situations and improving the applicability of the single-photon detector gating signal generation system. In some embodiments of the present invention, the frequency of the first sinusoidal branch 31 can also be adjusted.

[0052] In some embodiments of the present invention, such as Figure 2 and Figure 4 As shown, the gating circuit also includes a signal shaping circuit 34, an amplifier 35, and a capacitor 36. The gating signal is connected to the cathode of the avalanche photodiode 10 in sequence through the signal shaping circuit 34, the amplifier 35, and the capacitor 36. The first sinusoidal branch 31 contains a phase-locked loop (PLL) circuit, and the second sinusoidal branch 32 also contains a PLL circuit. The PLL circuits have a reference clock circuit. The PLL circuits can create and maintain a precise, stable, and clean frequency and phase relationship, which is beneficial for generating a stable gating signal, and thus beneficial for controlling the avalanche photodiode 10, thereby facilitating efficient and stable detection by the single-photon detector.

[0053] In some embodiments of the present invention, such as Figure 2 and Figure 4 As shown, the anode of the avalanche photodiode 10 is connected to an amplifier 41, a filter 42 and a comparator 43, which can be used for the detection signal output of the avalanche photodiode 10.

[0054] This invention also provides a method for generating a single-photon detector gating signal, which utilizes the single-photon detector gating signal generation system in any of the above embodiments to generate a gating signal acting on the cathode of an avalanche photodiode. Specifically, the method for generating a single-photon detector gating signal includes:

[0055] A bias voltage signal is generated using a bias voltage source;

[0056] The first sinusoidal voltage signal is generated using the first sinusoidal branch.

[0057] A second sinusoidal voltage signal is generated using the second sinusoidal branch.

[0058] The second sinusoidal voltage signal, the first sinusoidal voltage signal, and the bias voltage signal are used to generate a gating signal.

[0059] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A single-photon detector gating signal generation system, characterized in that, include: A bias voltage source is used to connect to the cathode of an avalanche photodiode and is configured to output a bias voltage signal. A gated circuit having a first sinusoidal branch and a second sinusoidal branch, wherein the first sinusoidal branch is configured to output a first sinusoidal voltage signal and the second sinusoidal branch is configured to output a second sinusoidal voltage signal; The frequency of the first sinusoidal voltage signal is greater than the frequency of the second sinusoidal voltage signal; The second sinusoidal voltage signal, the first sinusoidal voltage signal, and the bias voltage signal generate a gating signal that acts on the cathode of the avalanche photodiode; Based on the period of the first sinusoidal voltage signal, the gate signal has an amplitude greater than a preset value within one period or within a first number of consecutive periods, and the gate signal does not have an amplitude greater than the preset value within the next second number of consecutive periods.

2. The single-photon detector gating signal generation system according to claim 1, characterized in that, The gated circuit also includes a mixer; Both the first sine branch and the second sine branch are connected to the input terminal of the mixer, and the output terminal of the mixer is connected to the cathode of the avalanche photodiode. The second sinusoidal voltage signal is a modulation signal used to adjust the amplitude of the first sinusoidal voltage signal.

3. The single-photon detector gating signal generation system according to claim 2, characterized in that, The first sinusoidal voltage signal is A1sin2πf g t, A1 is the amplitude of the first sinusoidal voltage signal, f g The frequency of the first sinusoidal voltage signal is denoted as t, and t is a time parameter. The second sinusoidal voltage signal is A2sin2π(f g / N)t, A2 is the amplitude of the second sinusoidal voltage signal, N is the ratio between the frequency of the first sinusoidal voltage signal and the frequency of the second sinusoidal voltage signal, and N is an odd number; The signal obtained by combining the first sinusoidal voltage signal and the second sinusoidal voltage signal is A1A2sin2π(f g / N)t×sin2πf g t.

4. The single-photon detector gating signal generation system according to claim 1, characterized in that, The gating circuit also includes an adder; Both the first sine branch and the second sine branch are connected to the input terminal of the adder, and the output terminal of the adder is connected to the cathode of the avalanche photodiode.

5. The single-photon detector gating signal generation system according to claim 4, characterized in that, The first sinusoidal voltage signal is: A1sin2πf g t, A1 is the amplitude of the first sinusoidal voltage signal, f g The frequency of the first sinusoidal voltage signal is denoted as t, and t is a time parameter. The second sinusoidal voltage signal is A2sin2πf m t, A2 is the amplitude of the first sinusoidal voltage signal and is greater than A1, f m f is the frequency of the second sinusoidal voltage signal, t is the time parameter; g = (1+4k)*f m k is a positive integer; The signal obtained by combining the first sinusoidal voltage signal and the second sinusoidal voltage signal is: R f As feedback resistors, R1 is a resistor located between the first sine branch and the input terminal of the adder, and R2 is a resistor located between the second sine branch and the input terminal of the adder.

6. The single-photon detector gating signal generation system according to claim 1, characterized in that, The gating circuit also includes a signal shaping circuit, an amplifier, and a capacitor; The gating signal is connected to the cathode of the avalanche photodiode in sequence through the signal shaping circuit, the amplifier, and the capacitor.

7. The single-photon detector gating signal generation system according to claim 1, characterized in that, The frequency of the first sinusoidal branch can be adjusted, and the frequency of the second sinusoidal branch can be adjusted.

8. The single-photon detector gating signal generation system according to claim 1, characterized in that, The bias voltage signal is less than the breakdown voltage of the avalanche photodiode; The preset value is equal to the breakdown voltage.

9. A method for generating a gated signal for a single-photon detector, characterized in that, The system generates a gating signal acting on the cathode of an avalanche photodiode using the single-photon detector gating signal generation system as described in any one of claims 1 to 8; comprising: The bias voltage signal is generated using the bias voltage source; The first sinusoidal voltage signal is generated using the first sinusoidal branch. The second sinusoidal voltage signal is generated using the second sinusoidal branch. The second sinusoidal voltage signal, the first sinusoidal voltage signal, and the bias voltage signal are used to generate the gate signal.

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