CN100458383C

CN100458383C - Method for collecting snowslide signal of APD single photon detector

Info

Publication number: CN100458383C
Application number: CNB2005101238569A
Authority: CN
Inventors: 孙志斌; 杨捍东; 马海强; 翟光杰; 吴令安
Original assignee: Institute of Physics of CAS
Current assignee: Institute of Physics of CAS
Priority date: 2005-11-23
Filing date: 2005-11-23
Publication date: 2009-02-04
Anticipated expiration: 2025-11-23
Also published as: CN1758037A

Abstract

This invention discloses a method for extracting avalanche signals of the APD single photon detector including the following steps: after the triggering signals pass through a trigger delay unit, part of them is added into the cathode of APD after passing through a gated pulse control unit, then current samples are carried out at the anode to get the original signals, the other part is input into the trigger via the counting delay unit and the control unit, the original signals are sent into the trigger via a comparator as the clock of the trigger, which finishes the pulse extraction of APD avalanche signals triggered by the two parts of signals, part of the extracted pulses is fed back to a dead zone time control unit , the other part outputs signals from the output of the trigger and outputs pulse signals with controlled pulse width via a width control unit.

Description

The extracting method of APD single-photon detector avalanche signal

Technical field

The present invention relates to the quantum cryptography communication class, particularly relate to the extracting method of avalanche diode (APD) avalanche signal in a kind of single photon detection technique.

Background technology

The quantum cryptography communication technology is to have determined the characteristic that it maintains complete secrecy by the physics Heisenberg uncertainty principle, be based on the communication of light quantum, encrypted message loads on the single photon, and transmit by single photon, unknown quantum state can not be cloned, measure quantum and can change quantum state, the listener-in just can not eavesdropping information and be not found like this.In quantum secret communication, single photon detection has important effect, the optical signal detecting and the amplifying device that are used for single-photon detector mainly contain photomultiplier and avalanche photodide, photomultiplier is low at optical fiber communication wavelength coverage internal quantum efficiency, noise is big, dark current is big, and avalanche photodide is opposite with it, has quantum detection efficiency height, noise is little, advantages such as dark current is little, make avalanche photodide in quantum cipher communication system, progressively replace photomultiplier, but, because avalanche photodide itself exists distributed capacitance and junction capacity, the existence meeting of these electric capacity produces the differential disturbing pulse at the rising edge and the negative edge of gate-control signal, how from the differential disturbing pulse, to extract avalanche signal, become the big difficult point of one in the single-photon detecting survey technology; Avalanche diode intrinsic after the APD generation snowslide is oversize release time in addition, becomes the bottleneck that influences detector speed, improves the quantum cryptography transmission communication transmission rate.How after obtaining light pulse signal, to shorten another urgent problem that just becomes single photon detection release time of avalanche signal.

Summary of the invention

The purpose of this invention is to provide that a kind of speed is fast, antijamming capability is strong, simple in structure, dirigibility big, the experiment parameter scope is wide, output signal can adapt to the extracting method of the APD single-photon detector avalanche signal of different pulse widths requirements.

For achieving the above object, technical solution of the present invention is:

A kind of extracting method of APD single-photon detector avalanche signal, this method may further comprise the steps:

(1) with trigger pip through a trigger delays after a part deliver to the gating pulse control module, another part then passes through input trigger after count delay unit, the counting control unit, described trigger delays is a controlled delay circuit unit, the negative electrode that the gating pulse control module is added to APD behind certain width value again with the pulse-length modulation of institute's input signal makes APD enter light and triggers waiting status, carry out current sampling as the original signal of obtaining from the APD anode then;

(2) will deliver to comparer from the original signal that the APD anode is obtained, in comparer with comparer in the discriminating voltage that sets compare, filtering weak jamming signal, and with the conversion of signals that keeps become the TTL signal also input trigger as the clock of trigger;

(3) trigger is finished the DISCHARGE PULSES EXTRACTION of APD avalanche signal under the triggering of two paths of signals;

(4) part of the pulse of said extracted feeds back to the Dead Time control module, in this Dead Time control module, form high-level control signal and deliver to gating pulse unit and counting control unit respectively, gating pulse control module and counting control unit were closed in the time period of certain control, after the Dead Time control signal disappears, it is normal that gating pulse control module and counting control unit are recovered, through pulse signal that pulsewidth is controlled of output after the shaping of output width control module, this signal is exactly the single-photon avalanche signal that finally passes through shaping to the output terminal output signal of another part slave flipflop of described pulse simultaneously.

Further, in described step (four), the part of the pulse of described extraction feeds back to the Dead Time control module after by a switch control unit.

Said method is avoided the APD economize on electricity in the mode of gate and is held the differential signal that is produced, obtain real light pulse signal, and in case obtained light pulse signal, carry out avalanche diode immediately and suppress, shortened the recovery T.T. of avalanche signal, speed is fast, antijamming capability is strong, dirigibility is big, and the experiment parameter scope is wide, and the output signal of said method can adapt to the requirement of different pulse widths.

Description of drawings

The principle schematic that accompanying drawing 1 extracts for APD avalanche signal of the present invention;

The sequential chart that accompanying drawing 2 extracts for the APD avalanche signal;

Accompanying drawing 3 is the active inhibition sequential chart of APD avalanche signal;

Accompanying drawing 4 is APD avalanche signal time series analysis figure;

The embodiment circuit diagram that accompanying drawing 5 extracts for the APD avalanche signal.

Embodiment:

The extracting method of APD single-photon detector avalanche signal of the present invention comprises following process:

As shown in Figure 1, trigger pip A is through a trigger delays 1, this trigger delays 1 is a controlled delay circuit unit, a part is delivered to gating pulse control module 2 after trigger pip can being postponed a setting-up time, another part then passes through count delay unit 5, counting control unit 6 obtains input trigger 4 behind the TTL signal through twice time-delay and through width modulated, the purpose of this time-delay is control gate-control signal and the laser instrument synchronous working that produces the single photon signal, gating pulse unit 2 with the pulse-length modulation of its input signal to certain width value (can artificially regulate), the negative electrode that is added to APD again makes APD enter light and triggers waiting status, carry out current sampling as obtaining signal from the APD anode, this signal will comprise by the gating pulse signal, the avalanche signal that the single photon that caused differential signal of APD distributed capacitance and junction capacity and expectation obtain triggers, to deliver to comparer 3 from the signal that the APD anode is obtained, in comparer 3 with comparer 3 in the discriminating voltage that sets compare, this discriminating voltage can artificially be regulated, with filtering weak jamming signal, and with the conversion of signals that keeps become the TTL signal also input trigger 4 as the clock of trigger 4; Trigger 4 has been finished the DISCHARGE PULSES EXTRACTION of APD avalanche signal under the triggering of two paths of signals, the part of this pulse feeds back to Dead Time control module 10 by a switch control unit 8, in this Dead Time control module 10, form high-level control signal and deliver to gating pulse unit 2 and counting control unit 6 respectively, gating pulse control module 2 and counting control unit 6 were closed in the time period of certain control, after the Dead Time control signal disappeared, gating pulse control module 2 recovered normal with counting control unit 6.The output terminal output signal of another part slave flipflop 4 of described pulse is simultaneously through pulse signal that pulsewidth is controlled of output after 9 shapings of output width control module, this signal is exactly the single-photon avalanche signal that finally passes through shaping, trigger delay wherein, gating pulse, count delay, counting control, Dead Time, output pulse width can artificially be set.

The sequential that the APD avalanche signal extracts as shown in Figure 2, the gate-control signal that sends from gating pulse control module 2 is as the work trigger pip of APD, can obtain the original samples signal from the anode of avalanche diode, the distributed capacitance of APD snowslide pipe and differential undesired signal and the single-photon avalanche signal that junction capacity is caused have been comprised in the original samples signal, the original samples signal is compared with discriminating voltage in comparer 3, just from the original samples signal, identify first differential signal and avalanche signal, and be converted into Transistor-Transistor Logic level, the width value that in the count delay unit, counting controling signal is postponed first differential signal then, avoid first differential undesired signal, avoid second differential undesired signal by the width adjusting of counting control unit, like this counting controling signal of Xing Chenging just can the effective range of gate-control signal (be gate-control signal after first differential signal with second differential signal before high period between) in realize comparator output signal and counting controling signal mutually and computing, thereby catch the avalanche signal that single photon triggers, so just finished the extraction of APD avalanche signal.

The sequential of the active inhibition of APD avalanche signal as shown in Figure 3, under the cooperation of gating pulse signal and counting controling signal, trigger captures avalanche signal at the peak value place of avalanche signal, rising edge in this trigger pip triggers dead-time control circuit, the Dead Time control signal that triggers is closed gating pulse circuit and count control circuit at once, at this moment gating pulse signal and counting controling signal return to low level rapidly, stop the triggering of avalanche photodide and catching avalanche signal, avalanche diode is recovered rapidly, after the Dead Time control signal disappears, gating pulse circuit and count control circuit just recover original state, enter next measuring period, thereby improve the detection speed of avalanche signal.

The analysis of APD signal time as shown in Figure 4, in original signal, t ₁₁Be the time of first differential signal, t ₁₂Be the time of second differential signal, t _1LHBe the time of avalanche signal ascent stage, t _1HLBeing the time of avalanche signal decline stage, because the fall time of avalanche signal is longer, is 1us generally speaking, and this becomes the bottleneck that single-photon detector detects the avalanche signal speed, and can make t fall time of avalanche signal in active inhibition working method _1HL＜10ns, this has just improved the speed of detector greatly since differential signal is the junction capacity of avalanche photodide and distributed capacitance discharge and recharge cause, the time of discharging and recharging can be by the approximate treatment of t=5RC formula.Discharge resistance is than little many of charging resistor in side circuit, so charging resistor is only considered in approximate treatment, junction capacity and distributed capacitance value size are 0.3 ~ 0.6pF, charging resistor is the gate output resistance, be generally several kilohms, select the smaller device of output resistance in practice, so just can make t ₁₁And t ₁₂Less than 10ns, adjust the quiescent point of avalanche photodide, just can be with the rise time t of avalanche signal _1LH＜5ns, and the time span of whole signal is these four time sums, i.e. t=t ₁₁+ t ₁₂+ t _1LH+ t _1HL, t＜35ns from the above, a complete periodic signal also should comprise the low level time, periodic signal T＜50ns that the family can be complete like this, thus just can make the speed of detection of single-photon detector reach 20MHz.

Shown in the circuit diagram that Fig. 5 APD avalanche signal extracts, input end at signal uses 74F04,74F02 not gate and rejection gate constitute internal trigger signal and external trigger signal selecting switch, select through selector switch, trigger pip A enters trigger delay device DALLAS1023, under the control of Data Control end, trigger pip is postponed certain hour, dead band gauge tap through 74F02 and 74F04 formation is delivered to gating pulse control device DALLAS1023, modulation is delayed the pulse width of signal, be coupled to the negative electrode of APD then through C10, from sample resistance R5 output signal delivered to 8561 comparers and the relatively back clock as trigger 74F112 of discriminating voltage at the APD anode; With the 6 pin signals of U10 asynchronous resetting signal as trigger; Simultaneously the 6 pin output signals of U10 are delivered to counting control trigger delay DALLAS1023, delayed signal is given counting control unit DALLAS1023 by the dead band gauge tap that U14 constitutes, through the signal of its modulation J input signal as trigger 74F112; Deliver to Dead Time control device DALLAS1023 from the signal one tunnel of 74F112 positive output,, be used for controlling the Push And Release of gate pulser spare and technology control device through Dead Time control signal of its output.TTL output control DALLAS1023 is delivered on another road, and the width modulated of this signal is exported to the width that is complementary with external equipment.

U1 among the figure, U2, U3, U4 is an optoisolator spare, finishes the isolation of control module data and APD data, the phase mutual interference between the minimizing, 74LS138 and 74ALS04 are decoded as the data latch control signal of above-mentioned DALLAS1023 with control signal, cooperate controller to finish latching of data.

Claims

1, the extracting method of APD single-photon detector avalanche signal is characterized in that: this method may further comprise the steps:

2, the extracting method of APD single-photon detector avalanche signal as claimed in claim 1 is characterized in that: in described step (four), the part of the pulse of described extraction feeds back to the Dead Time control module after by a switch control unit.