Electro-Optic SamplingElectro-Optic Sampling

John WhitakerJohn WhitakerCenter for Ultrafast Optical Science

University of Michigan, Ann Arbor, MI

A technique which utilizes short-pulse lasers and electro-opticmaterials for measuring electrical transients with extremely hightemporal resolution, < 300 femtoseconds (3 x 10^-13 seconds).This instrument is the fastest (highest bandwidth) oscilloscopeever developed.

Electro-Optic Sampling System Schematic

to lock-inamplifier

+

eyepiece

illumination

dichroic beam

EXTERNAL ELECTRO-OPTIC SAMPLING SCHEME

probe beam in(arrive atdelayed timesof t + n.At)

electro-opticprobe crystal

semiconductorsubstrate

switchbias

Electro-Optic Probe

1 THz Bandwidth Samplinq

0.6

0.6

0.4

0.2

photoconductive

probe

0.5 1.0 1.5 2.0 2.5

Time (picoseconds)

Impact of Optics on Ultrafast Electronics

1000 ps i: 1-GHz Bandwidth: .

0.1 ps

1

50 GHz _. 90 GHz.900 GHz. 2 THz :. -

Photo-Real-Time Single-Shot Electronic Josephson conductive

scope ScopeElectro-Optic

Sampling Sampling Sampling Sampling

External Electro-Optic Sampling with LiTaO,

l Sensitivity -+ typically: 1 mV/JHz+ enhanced: < 300~VlJHz--f can measure < 10^-7 Io--f linearity: 1% for +/- 160 V

l Laser

l Probe

l System

-+ modulation frequency: typically 2-3 MHz-+ repetition rate: 90 MHz-$ power: 100 mW/beam

-+ half-wave voltage: 2.7 kV-+ permittivity: ~43--) reduced to ~3 with use of e-o polymers+ effect on transmission line impedance: delta(Zo) = 10%

-+ bandwidth: > 1 THz-+ temporal response: < 300 fs-+ dynamic range: typically 100 dB

input

samplinggate

sampledsignal

Sampling of Repetitive Signals-Short Gate Duration

I

t1 time

t2 . . . . time. .. ... .

. . . . . . . . . . . . . . . . . . . . .I0 delay time

delta(t) = t2 - t1