1 Adv - PowerPoint Presentation

Slide1

1

Advanced active quenching circuits for single-photon avalanche photodiodes

Mario StipčevićPhotonics and Quantum optics Research GroupCenter of excellence for advanced materials and sensing devices,Ruder Boskovic Institute, Zagreb, CroatiaE-mail: Mario.Stipcevic@irb.hrURL: http://cems.irb.hr/en

SPIE Defense and Commercial Sensing 2016

,

Baltimore, Maryland, USA, Apr 21, 2016Slide2

2

Si SPAD based photon detector

Single photon detector – a device that produces one standardizedlogical pulse upon each successful detection of a photon. Slide3

3

We use commercial “thick reach-through” Si Single-Photon-capableAvalanche photo Diode

(SPADs) SAP500-T8 (Laser Components)operated in Geiger mode + home-made electronics comprising:Active Quenching Circuit (AQC)TEC temperature controllerLow voltage generator (~25V)High voltage generator (100~500V)

Detection imperfections come from

: SAP500 SPAD

Diode physics

ElectronicsSlide4

4

A realistic active quenching loop circuit with a double feedback (left);and its timing diagram (right).

M. Stipcevic, Appl.Opt. 48,1705-14(2009) Active quenching circuit (AQC)Slide5

5

APD:

Detect. efficiency <1AfterpulsingTiming jitterSuper-linear behaviorElectronics:Dead timeMax. count rateVariable dead t.

& eff.

Twilighting

Blindability

Detector imperfections

Distribution

of pulse interval times of a realistic detector

Input:

CW random light (LED)

Shown is histogram of time intervals between subsequent output

pulses (

note

: not every pulse corresponds to a real photon detection). Slide6

6

Jitter and detection delay vs

detection frequencyJitter and shift as funct. of detection frequency, at 635nmUsed 225ps FWHM pulsed laser triggered at 10MHz. Attenuation adjusted to set the desired detection frequency in the range 0.05-1MHz.Comparison of a custom-made detector and a few commercial

Excelitas

SPCM-AQRH

IdQuantique

ID100 Home-made

τ

-SAP

Method as described in

Opt. Express.

18 (2010) 17748-17459Slide7

Excelitas

SPCM-AQR-12 single photon timing performance. At about 500kHz a secondary peak appears and at 1M there is on big blob with FWHM ~

1ns + 1.6ns shift. Dead time ~50 ns.(Plots show result for Gaussian sigma of the fit. Laser and detector are convoluted.)Slide8

IdQuantique’s

ID100 is a low-efficiency small diameter (20um) APD specialized for best timing of 50ps FWHM. Good: Peak stability is excellent. Bad: (1) long tail,(2) resolution becomes worse with detection frequency.

Dead time ~50 ns.Slide9

Home made -SAP

(fast version). Excellent time resolution

, excellent resolution stability even at highest tested detection frequency, excellent stability of delay, lowest detection delayall at high detection efficiency => 4 improvements vs. commercial solutions. Dead time ~24 ns.Slide10

Comparison of 3 detectors

regarding time resolution (jitter)and peak stability

as functions of thedetection frequency.(Laser pulse width subtracted.)The stabilities of resolution and delay of tau-SAP arebetter than stabilityany major brand of detector.Slide11

11

Twilighting

Twilighting is an effect of sensitivity of detector during the dead timeIt is a period of bias voltage recovery when the SPAD is biased above Geiger breakdown and can generate an avalanche but it will generate an output pulse only after the dead time => detection propagation delay time shift.This interval is named the “twilight zone” (yellow shaded)Slide12

12

Twilighting (detection of photons during dead time)Time shift of photon detection vs. detection frequency

Distributions of detection waiting time for MPD50 (dead time 78.1 ns) when light pulses are apart by: 40 ns

(second

photon not observed = noise) (left), 60 ns (second photon arrived in the twilight zone but observed after the dead time) (middle), and 80 ns (second photon arrived and observed after the dead time). Fit parameter Sigma is one Gaussian sigma of the fitted curve.

Micro Photon Devices

SPD-050Slide13

13

Twilighting (detection of photons during dead time)Time shift of photon detection vs. detection frequency

Distributions of detection waiting time for PerkinElmer SPCM-AQR (dead time 29.5 ns) when light pulses are apart by: 23 ns {second photon in the twilight zone) (left), 30 ns (right). Jitter in the twilight zone seems to be improved far beyond possible limits for the SPAD – it is an effect of a very precise dead time of the SPCM.

PerkinElmer

SPCM AQRSlide14

14

Dead time proximity detection delay

Time shift between the true and measured photon arrival time for the second photon in a pair (if both photons have been detected), as a function of the time interval between the two incoming photons (left). Time resolution (jitter) of the second photon in a pair if both photons have been detected (right).Slide15

15

Electronics artifacts

Twilighting is imposed intentionally in order to avoid atomic race condition between end of quench and start of amplifier sensitivityWhat if twilight zone is too narrow and amplyfier becomes sensitive while SDAD is still generating signal⇒ re-triggeringIn older Perkin Elmer SPCM AQR detectors (Rev. F, ~year 2003) we

see strong retriggering (we do not see this in newer versions

):

We can reproduce this in our circuit by tightening the twilight zone.Slide16

16

Other electronics issues

High voltage SPAD bias stability upon sudden supply current jump:0 mA → 1 mA (left); 1 mA → 0 mA (right).

A major

manufacturer

Home-made power supplySlide17

17

In this study, we differ “standard” imperfections (widely accepted

) :non-unity detection efficiencydead timedark countsafterpulsingjitterAnd “hidden” imperfections:variation of jitter with detection freqency (peak width)variation of detection delay with frequency (peak position) variation of dead time with detection effiniency

Dead time proximity effects

Retriggering and other electronics issues.

We illistrate

that commercial detectors are plagued with

the

hidden

imperfections

(not specified in the datasheets nor widely recognized).

Hidden

imperfections cannot be neglected.Slide18

18

In quantum information and communication experiments performed by photons

:afterpulsing and twilighting may create false events, false correlations in data, information leakage;unstable jitter and time shifts may cause loss of data, oss of coincidences or false coincidences.That is why experimentalists in quantum information often resort to their own devices in building of detectors that are optimized for the given experiment.Slide19

19

An advanced AQ circuit with significant improvement in hidden imperfections without sacrifising performance in standard imperfections.

Custom (home) made detectorAC coupling of quench signal replaced by galvanic coupl.

Peak shift >100ps for photons >28 ns apart

Twilight zone <1.5 ns

Jitter virtually constant 160

ps

FWHMSlide20

20

Standard imperfections example

Polarization qubit analysis in orthogonal basis (polarizing beamsplitter): (highest entropy α2=β2=½)

PBS

Depending on which detector “clicks”, 0 or 1 is generated per each detected photon.

The same configuration used in:

a receiver station of QKD

and in

a quantum random number generator (QRNG).

Polarization analysis setup comprises polarizing beamsplitter (PBS) and two single-photon detectorsSlide21

21

We found that correlations are solely due to

detector imperfections:Afterpulsing → positive, dead time → negative autocorrelation.In this example hidden imerfections are significantly less important.M. Stipcevic, D. J. Gauthier, Proc. SPIE DSS, paper 87270K, 29 April - 3 May 2013,

Baltimore, Maryland,

USA

Serial autocorrelation coefficient as a function of photon detection rate Slide22

22

Application: Ultra-fast QKD with hyper-entangled photons, entangled simultaneously

in: photon number, polarization, and time bin.One “frame” consists of 1024 time bins (slots) of ~260 ps (+) two-photon entanglementPump power is set such that Alice and Bob receive about 1 photon per time frameFor a successful communication instance Alice and Bob must receive photons from an entangled pair in the same time bin

T

wilighting

and other detection time shifts greater than ~100-200

ps

cause

direct errors

(BER)

in time-bin entanglement readout

Hidden imperfections exampleSlide23

23

1. Autocorrelation

Probability of Alice and Bob detecting a photon in the same bin(distinguishability)

Slide24

24

Longer dead time promotes losses, larger twilighting promotes errors

Finaly, secret key channel capacity (after error correction): 2.4 qubits/photon with

SPCM AQRH-12

3.

6

qubits

/photon

estimated with the custom-made after error correction

In this example, due to tight coincidence, dark counts and less so afterpulses are supressed but hidden imperfections play a major role.

Slide25

Detection efficiency at 635nm

(InPho = 75%, SPCM-AQR = 65%, ID100 = 23%, SPD-050 = 40%)Short, fixed dead time (24 ns)

Total visible afterpulsing probability = 3.2%Jitter 156 ps FWHM at a rate < 100 kcps 164 ps FWHM at a rate 1 Mcps 184 ps FWHM at a rate 4 Mcps

Peak position stability 0 – 4

Mcps

< 20

ps

Uses blanking circuit to shrink twilight zone to

<1.5

ns

The shortest detection delay (11ns faster than SPCM or Id100)

The largest diameter of the flat top of the active region

(

InPho

=500um, SPCM-AQR =180um, ID100

≤

50um, SPD-050

≤100um

)

Dark counts at the level of 1-2 kHz at -25

o

C

, while <25 cps have been observed on selected APDs.

Custom-made detector,

Under DARPA

InPho

program