MIT Optics & Quantum Electronics Group Lasers and RF-Timing Franz X. Kaertner Department of Electrical Engineering and Computer Science and Research Laboratory.

MIT Optics & Quantum Electronics Group

Lasers and RF-Timing

Franz X. Kaertner

Department of Electrical Engineering and Computer Science and

Research Laboratory of Electronics,Massachusetts Institute of Technology,

Cambridge, USA


Outline

I. System Overview

II. Timing Distribution

III. RF-Synchronization

IV. Some Experimental Results

V. Photo-Injector

VI. Long Seed Pulse Generation

VII. Conclusion


Facility conceptFacility concept

0.3 nm 0.1 nm

UV Hall X-ray Hall

Nanometer Hall

SC Linac4 GeV2 GeV1 GeV

1 nm

0.3 nm

100 nm

30 nm

10 nm

10 nm

3 nm

1 nm

Master oscillator

Pump laser

Pump laser

Seed laser

Seed laser

Seed laser

Pump laser

Fiber link synchronization

Injector laser

Undulators

Undulators

Undulators

Future upgrade to 0.1 nm at 8 GeV

SC Linac

W.S. Graves, MIT Bates Laboratory


Timing Distribution

Ph

oto

-Inj

.t

= 1

00 fs

Gun

Optical Master OscillatorMode-locked Laser

RF-Clock100 MHz

Timing Stabilized Fiber Links

10kHz5s

Pulsed Klystron

Linac

SC-Accel.1.3 GHzt=200 fs

Linearizer3.9 GHzt=10 fs

RF-Switch0.65 GHzt=200 fs

Undu-lator

HH

G-S

eed

t =

10

fs

Pro

be L

ase

rt

= 1

0 fs

t: Required Timing Jitter in Each Section10 fs ~ 3m


CrossCorrelator

Timing Stabilized Fiber Links (<1km)

Fiber

ML - Laser

PZT

Fixed Length L

Assuming no fiber length fluctuations faster than 2L/c.


Cooperation on Frequency Metrology and Timing Distribution

Both at MIT and JILA-NIST: MURI-Projects funded by ONR

Frequency Metrology and

Femtosecond Technology for Optical Clocks

MIT:E. P. Ippen (PI)Y. Fink F. KaertnerD. KleppnerL. KolodziejskiJ. ShapiroF. Wong

JILA-NIST:J. Ye (PI)S. DiddamsL. Holberg…..

J. Ye, JOSA B 20, 1459 – 1469 (2003)


Experimental Results on Transmission of Optical Frequency Standards

By active fiber induced phase noise cancelation


Sub-10 fs RF-Synchronization(Mike Perrott, MTL, MIT-Proprietary Information)

PhaseModulator

4

VCOLoopFilter

-1.0

-0.5

0.0

0.5

1.0

w0 / (L

/)1/2

20151050Cavity Length, L / cm

RF: f = m fR

Recovered from optical pulse train

RepetitionRate: fR

PBS


Experimental Results on Synchronization

Synchronization of a 5fs Ti:Sapphire laser @ 800 nmand a 30 fs Cr:Forsterite laser @ 1300 nm

with 0.3 fs timing jitter measuredfrom 1mHz to 2.3 MHz.


5fs Ti:sapphire Laser

Laser crystal:

2mm Ti:Al2O3

PUMP

OC 1

OC 2

Base Length = 30cm for 82 MHz Laser

L =

20

cm

BaF2 - wedges

1mm BaF2


Laser Spectra

-60

-50

-40

-30

-20

-10

0

Spec

tral

Pow

er [

log]

1600140012001000800600Wavelength [nm]

Ti:sapphire Cr:forsterite

5 fs 30 fs


Output(650-1450nm)

Ti:sa

Cr:fo

3mm Fused Silica

SFG

SFG

Rep.-RateControl

(1/496nm = 1/833nm+1/1225nm).

Δt

0V

Balanced Cross-Correlator


Balanced Cross-Correlator Output(650-1450nm)

Ti:sa

Cr:fo

3mm Fused Silica

SFG

SFG

Rep.-RateControl

(1/496nm = 1/833nm+1/1225nm).

-

+

Δt

0V-

Δt

+GD

-GD/2

Δt

0V


Balanced Cross-Correlator


Measuring the residual timing jitter

Output(650-1450nm)

JitterAnalysis

SFG

Ti:sa

Cr:fo

3mm Fused Silica

SFG

SFG

Rep.-RateControl

(1/496nm = 1/833nm+1/1225nm).

GD

-GD/2


Experimental result: Residual timing-jitter

The residual out-of-loop timing-jitter measured from 10mHz to 2.3 MHz is 0.3 fs (a tenth of an optical cycle)

Long Term Drift Free

1.0

0.8

0.6

0.4

0.2

0.0Cro

ss-C

orre

lati

on A

mpl

itud

e

-100 0 100

Time [fs]

100806040200Time [s]

Timing jitter 0.30 fs (2.3MHz BW)



1 Laser System & Synchronization

High Harmonic Generation

> 10 nJ

Sub fs – 10 fs, 2ps

1-10 kHz

@ 8,30,200 nm

Photo-Injector:

10-20 ps Pulses

1-10 J

1-10 kHz

@ 266 nm(conv. NLO)

Fiberlink + Synchronization

LINAC FELE-beam

X00 m

10 fsTiming Jitter


Directly Diode-pumped Photo-Injector

To achieve a homogeneous e-beam bunch

Yb:fiber amplifierIPG-Photonics

20ps, 10J, 1-10 kHz@ 1064 nm

4th-Harmonic

20ps, 1J, 1-10 kHz@266 nm

Yb:YAG, 1ps

rep. Rate100 MHz

Pulse Selector

Acusto-OpticProgramablePulse Shaper

(Dazzler,Fastlight)

Temporal: Flat-top shaped


Long Pulse Seed Generation2ps, 1mJ @ 200 (266) nm

Yb: YAGCPA

2ps, 20mJ, 1-10 kHz@1064 nm

4th-Harmonic

2ps, 1mJ, 1-10 kHz@ 200 (266) nm

Yb:YAG, 2ps

rep. Rate100 MHz

Pulse Selector

Acusto-OpticProgramablePulse Shaper

(Dazzler,Fastlight)


• Seeding needs 10 fs timing distribution over 300m distances

(rel. precision 10-8). Can be accomplished by length stabilized

fiber links.

• Fiber noise eliminated by active feedback.

• Scheme for phase stable RF-regeneration has been outlined

• Less than 0.3 fs between independent lasers has

been demonstrated, Optical Clock distribution.

• Photo-Injection Laser: Mode-locked Yb:YAG laser and amplifier

• Long wavelength seed: Mode-locked Yb:YAG laser and CPA

Conclusions

MIT Optics & Quantum Electronics Group Lasers and RF-Timing Franz X. Kaertner Department of Electrical Engineering and Computer Science and Research Laboratory.

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