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
MIT Optics & Quantum Electronics Group
Outline
I. System Overview
II. Timing Distribution
III. RF-Synchronization
IV. Some Experimental Results
V. Photo-Injector
VI. Long Seed Pulse Generation
VII. Conclusion
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
CrossCorrelator
Timing Stabilized Fiber Links (<1km)
Fiber
ML - Laser
PZT
Fixed Length L
Assuming no fiber length fluctuations faster than 2L/c.
MIT Optics & Quantum Electronics Group
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)
MIT Optics & Quantum Electronics Group
Experimental Results on Transmission of Optical Frequency Standards
By active fiber induced phase noise cancelation
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
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.
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
Laser Spectra
-60
-50
-40
-30
-20
-10
0
Spec
tral
Pow
er [
log]
1600140012001000800600Wavelength [nm]
Ti:sapphire Cr:forsterite
5 fs 30 fs
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
Balanced Cross-Correlator
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
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)
MIT Optics & Quantum Electronics Group
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
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
MIT Optics & Quantum Electronics Group
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)
MIT Optics & Quantum Electronics Group
• 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