Transcript filburt.mit.edu

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 concept
Master oscillator
Seed
laser
UV Hall
Fiber link synchronization
Pump
laser
Seed
laser
X-ray Hall
Pump
laser
Undulators
100 nm
Injector
laser
30 nm
Undulators
1 nm
10 nm
0.3 nm
0.3 nm
SC Linac
1 GeV
2 GeV
SC Linac
0.1 nm
4 GeV
10 nm
Future upgrade to 0.1
nm at 8 GeV
3 nm
1 nm
Undulators
Seed
laser
Nanometer Hall
W.S. Graves, MIT Bates Laboratory
Pump
laser
MIT Optics & Quantum Electronics Group
Timing Distribution
Gun
Linac
Probe Laser
Dt = 10 fs
Photo-Inj.
Dt = 100 fs
10kHz
5ms
Pulsed
Klystron
SC-Accel. Linearizer RF-Switch
1.3 GHz 3.9 GHz 0.65 GHz
Dt=200 fs Dt=10 fs Dt=200 fs
HHG-Seed
Dt = 10 fs
RF-Clock
100 MHz
Optical Master Oscillator
Mode-locked Laser
Undulator
Dt: Required Timing Jitter in Each Section
10 fs ~ 3mm
MIT Optics & Quantum Electronics Group
Timing Stabilized Fiber Links (<1km)
PZT
Cross
Correlator
Fiber
Fixed Length L
ML - Laser
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. Kaertner
D. Kleppner
L. Kolodziejski
J. Shapiro
F. Wong
JILA-NIST:
J. Ye (PI)
S. Diddams
L. 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)
w0 / (lL/)
1/2
1.0
0.5
0.0
-0.5
-1.0
0
Repetition
Rate: fR
5
10
Cavity Length, L / cm
15
20
l
4
PBS
Phase
Modulator
RF: f = m fR
Recovered from
optical pulse train
VCO
Loop
Filter
MIT Optics & Quantum Electronics Group
Experimental Results on Synchronization
Synchronization of a 5fs Ti:Sapphire laser @ 800 nm
and a 30 fs Cr:Forsterite laser @ 1300 nm
with 0.3 fs timing jitter measured
from 1mHz to 2.3 MHz.
MIT Optics & Quantum Electronics Group
5fs Ti:sapphire Laser
1mm BaF2
OC 1
Laser crystal:
2mm Ti:Al2O3
f = 10o
L = 20 cm
PUMP
BaF2 - wedges
OC 2
Base Length = 30cm for 82 MHz Laser
MIT Optics & Quantum Electronics Group
Laser Spectra
0
Spectral Power [log]
-10
-20
-30
-40
Ti:sapphire
Cr:forsterite
5 fs
30 fs
-50
-60
600
800
1000
1200
Wavelength [nm]
1400
1600
MIT Optics & Quantum Electronics Group
Balanced Cross-Correlator
Output
(650-1450nm)
Δt
Cr:fo
Ti:sa
(1/496nm = 1/833nm+1/1225nm).
SFG
Rep.-Rate
Control
SFG
0V
3mm
Fused Silica
MIT Optics & Quantum Electronics Group
Balanced Cross-Correlator
Output
(650-1450nm)
Δt
Δt
Cr:fo
Δt
-GD/2
Ti:sa
(1/496nm = 1/833nm+1/1225nm).
SFG
Rep.-Rate
Control
0V
+-
+
-
SFG
3mm
GD
Fused
Silica
MIT Optics & Quantum Electronics Group
Balanced Cross-Correlator
MIT Optics & Quantum Electronics Group
Measuring the residual timing jitter
Output
(650-1450nm)
Cr:fo
Ti:sa
Jitter
Analysis
SFG
-GD/2
(1/496nm = 1/833nm+1/1225nm).
SFG
Rep.-Rate
Control
SFG
3mm
GD
Fused
Silica
MIT Optics & Quantum Electronics Group
Cross-Correlation Amplitude
Experimental result: Residual timing-jitter
Time [fs]
1.0
-100
0
100
0.8
0.6
Timing jitter 0.30 fs (2.3MHz BW)
0.4
0.2
0.0
0
20
40
Time [s]
60
80
100
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
MIT Optics & Quantum Electronics Group
MIT Optics & Quantum Electronics Group
1 Laser System & Synchronization
Fiberlink + Synchronization
Photo-Injector:
X00 m
10-20 ps Pulses
High Harmonic
Generation
> 10 nJ
1-10 mJ
Sub fs – 10 fs, 2ps
1-10 kHz
1-10 kHz
@ 266 nm
(conv. NLO)
@ 8,30,200 nm
10 fs
Timing Jitter
E-beam
LINAC
FEL
MIT Optics & Quantum Electronics Group
Directly Diode-pumped Photo-Injector
To achieve a homogeneous e-beam bunch
Temporal: Flat-top shaped
Yb:fiber amplifier
IPG-Photonics
Yb:YAG,
1ps
rep. Rate
100 MHz
Pulse
Selector
Acusto-Optic
Programable
Pulse Shaper
(Dazzler,
Fastlight)
20ps, 10mJ, 1-10 kHz
@ 1064 nm
4th-Harmonic
20ps, 1mJ, 1-10 kHz
@266 nm
MIT Optics & Quantum Electronics Group
Long Pulse Seed Generation
2ps, 1mJ @ 200 (266) nm
Yb: YAG
CPA
Yb:YAG,
2ps
rep. Rate
100 MHz
Pulse
Selector
Acusto-Optic
Programable
Pulse Shaper
(Dazzler,
Fastlight)
2ps, 20mJ, 1-10 kHz
@1064 nm
4th-Harmonic
2ps, 1mJ, 1-10 kHz
@ 200 (266) nm
MIT Optics & Quantum Electronics Group
Conclusions
• 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
MIT Optics & Quantum Electronics Group