Time walk compensation of a SPADwith a linear photodetection

Etienne SAMAINRobert Dalla

Observatoire de la Côte d’Azur - CERGA France

Ivan Prochazka

Czech Techinal University Czech Republic

Specifications

Multi-photons mode with a dynamic of 104

Time stability below 1 ps over 1000 s

Precision better than 20 ps rms

Insensitive to the laser pulse width (20 - 200 ps)

Asynchronous detection mode

Silicon Sensor ADH230 SPADTime walk and precision

-600

-500

-400

-300

-200

-100

0

0.01 0.1 1 10 100 1000 10000 100000

N & <N>

Tim

e W

alk

(ps)

0

5

10

15

20

25

30

35

40

45

Rm

s (p

s)

Time WalkDiode Rms = f(<N>)Statistic RmsDiode Rms = f(N)

Photon statistic

( )LiniGei N,Npr

34,0

10lnN ⋅⋅

τ≈σ

LinGei Nr

r1N

−=

GeiN

LinN

iN

( ) linlinilin

i

NNNNNlini r)r1(CN,Np −−=

Photon statistic

Time walk : 100 ps/decader = 0.5

0

5

10

15

20

25

30

35

40

45

1 10 100 1000 10000 100000

Photon number Ni

Rm

s(p

s)

Statistic RmsDiode Rms = f(N)

Synoptic of T2L2 Space detection

Synoptic of Ground detection

Space segment prototype

Linear Photodetection

Avalanche photodiode in GainMode (RCA 902S)

Low noise integrator amplifier

Min threshold level < 100 hυ e-

Dynamic: 1040

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 5 10 15 20 25 30 35 40 45t (ns)

Am

plit

ud

e (V

)

Analog to digital converter

Resolution: 16 bits

Input bandwidth: 200 MHz

Linearity error: 1.3 bits rms

Precision: 1.3 bits rms-20

-15

-10

-5

0

5

10

15

20

-2 -1 0 1 2Input (Volts)

Lin

eari

ty (

bit

s)

Non linear photodetectionSPAD: Silicon Sensor AD230

0

20

40

60

80

100

120

140

0 200 400 600 800 1000t (ps)

Co

un

ts

SSOAD230 N°7Rms: 39 ps rms532 nm FWHM: 20 ps<N> = 0.08 hv

Precision and time walkOverall instrument

0

50

100

150

200

250

300

350

10 100 1000 10000 100000 1000000 10000000

< Photon number >

Tim

e w

alk

(ps)

.

0

2

4

6

8

10

12

14

16

Pre

cisi

on

rm

s (p

s)

.

Time walk

precision

Time stability @ 532 nm 10 HzOverall instrument

0.1

1

10

0.1 1 10 100 1000τ (s)

σx

(ps)

<N> = 1000 hvT0 = 0,1 s532 nm, FWHM = 20 ps

Time stability @ 778n nm 1 kHz Overall instrument

0.01

0.1

1

10

100

0.001 0.01 0.1 1 10 100τ (s)

σx

(ps)

<N> = 1000 hvT0 = 0,001 s778 nm, FWHM = 20 ps

SPAD K14 100 µmPrecision - Single photon mode

0

50

100

150

200

250

300

350

400

450

500

0 200 400 600 800 1000t (ps)

Co

un

ts

K14 100 µmRms: 21 ps rmsFWHM: 55ps532 nm FWHM: 20 ps<N> = 0.16 hv

0

40

80

120

160

200

240

-80 -60 -40 -20 0 20 40 60 80

Position (µm)

Tim

e w

alk/

rm

s (p

s)

0.01

0.1

1

Rel

ativ

e ef

fici

ency

Time walk

Rms

Relative Efficiency

SPAD K14 100 µmCenter-edge effect

SPAD K14 100 µmPrecision & TW - Multi photon mode

0

50

100

150

200

250

300

0 1 10 100 1000 10000 100000

< Photon number>

Tim

e w

alk

(ps)

0

5

10

15

20

25

30

Pre

cisi

on

rm

s (p

s)

Time walk

precision

Conclusions

Time walk compensatedPrecision: 15 - 3 ps over the whole dynamicTime stability better than 1 ps over 1000 s Insensitive to the laser pulse width (20 - 200 ps)Asynchronous detection mode

SPAD K14: the performances will be 2 times better

Chronograph

Light pulse

Linear photo detection

Integrator

Excess bias voltage

Light pulse SPAD

Output signal