The GEO 600 Laser System LIGO-G010366-00-Z
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Q09/2001 The GEO 600 Laser System LIGO-G010366-00-Z V. Quetschke°, M. Kirchner°, I .Zawischa*, M. Brendel*, C. Fallnich*, S. Nagano + , B. Willke° + , K. Danzmann° + , and the GEO600 Team *Laser Zentrum Hannover, Hollerithallee 8, D-30419 Hannover, Germany ° Universität Hannover, Institut für Atom- und Molekülphysik, Callinstraße 38, D-30167 Hannover, Germany + Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Aussenstelle Hannover, Callinstraße 38, D-30167 Hannover, Germany
description
The GEO 600 Laser System LIGO-G010366-00-Z. V. Quetschke°, M. Kirchner°, I .Zawischa*, M. Brendel*, C. Fallnich*, S. Nagano + , B. Willke° + , K. Danzmann° + , and the GEO600 Team *Laser Zentrum Hannover, Hollerithallee 8, D-30419 Hannover, Germany - PowerPoint PPT Presentation
Transcript of The GEO 600 Laser System LIGO-G010366-00-Z
Q09/2001
The GEO 600 Laser SystemLIGO-G010366-00-Z
V. Quetschke°, M. Kirchner°, I .Zawischa*, M. Brendel*, C. Fallnich*, S. Nagano+, B. Willke°+, K. Danzmann°+,
and the GEO600 Team
*Laser Zentrum Hannover, Hollerithallee 8, D-30419 Hannover, Germany
°Universität Hannover, Institut für Atom- und Molekülphysik, Callinstraße 38, D-30167 Hannover, Germany
+Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Aussenstelle Hannover,
Callinstraße 38, D-30167 Hannover, Germany
Q09/2001
Scheme GEO600 PSL
m ode cleaners
in terferom eter
in jection locked laser
am pltitude contro l frequency contro l
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Scheme of the Injection Locked Laser System
Pound-Dreverlocking e lectr.
servo
EOMEOM
m aster oscillator
pum p diodes
slave laser
isolatoror
from In terferom eter
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Master: Monolithic Nd:YAG NPRO• 800 mW single frequency• RRO and intensity noise suppression
(> 100 Hz) by electronic feedback• Frequency control by
– temperature • 3 GHz/K (dc) • bandwidth 1 Hz
– piezo • 2 MHz/V• bdw. typ 50 kHz limited by mech.
resonances – pump power
• 1 MHz/mA (dc)• 1/f dependency f >100 Hz• bdw. 100 kHz• no observable beam pointing
• External EOM for fast phase control
808 nmlaser crystal
1064 nm
Nd:YAG
PBS
diode laser
PZT
feedb. servo.
TEC
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Slave: Quasi monolithic Nd:YAG Laser
bow-tie ring with two end-pumped rods
• > 12 W, M2 < 1.1, DOP > 98%
• > 35 % optical efficiency
• 1 midrange piezo length actuator– 2.5 µm (2.5 GHz) / -15 to 300 V– max. Voltage -100 V to 500V – resonances > 50 kHz, – bandwidth 15-20 kHz– dc tilt typ. 10 µrad / µm
• Quasi monolithic design– no manually movable resonator parts– low thermal expansion spacer
Invar: = 8x10-7/K -> 225 MHz/K(air at 1000 hPa -> -250 MHz/K) (Alu: =24x10-6/K -> 6.7 GHz/K)
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Slave: Quasi monolithic Nd:YAG Laser
1 10 100 1000 1000010-5
10-4
10-3
10-2
10-1
100
101
102
103
104
105
quasi monolithc slave relative to stabilized NPRO
calculated influence on system with 1 MHz locking range and 1 kHz servo
Freq
uenc
y Fl
uctu
atio
ns [H
z/H
z-1
/2]
Frequency [Hz]Slave influence on frequency noise • comparable with free running master
(not injection-locked)
• follows stabilized master (when injection-locked)
Piezo range requirements (calculated):• 25 MHz / K
• 80 MHz / mbar : 50 mbar p-p: 4 GHz
Deviation from center of locking range• RMS 1 Hz -100 kHz: ca. 500 Hz which is 3x10-4 of locking range
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Short Term System Performance
• Locking range 1.6 MHz
• 94% visibility at first mode cleaner achieved
• No influence of slave to system frequency stability observable
• Amplitude prestabilization at detection band frequencies ...
Q09/2001
Modecleaner Frequency Noise
• The out-of-loop frequency noise at the first modecleaner: 10 mHz
Q09/2001
Autolock Slave to Master
• State (locked/unlocked) distinguished by output power
• Ramp slave cavity length to achieve transient injection lock
• Keep lock by switching from ramp to servo
• Typ. lock aquisition time 5 s (max. 20 s)
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Autolock Performance
0 2 4 6 8 10 12 14 16-8
-7
-6
-5
-4vo
ltage
[V]
auto lock perfom ance - se t1
0 2 4 6 8 10 12 14 16-0.05
0
0.05
volta
ge[V
] SL error
0 2 4 6 8 10 12 14 16-2
0
2
4
volta
ge[V
]
tim e [sec]
SL PZT feedback
PD D C out
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Intensity Noise Control – inloop
100
101
102
103
104
105
frequency (H z)
10-9
10 -8
10 -7
10 -6
10 -5
10 -4R
IN(1
/H
z)
free running, in j.lockin loopanalyzer no ise @ C H 1 range 501m Vpk
10.08.01 ; HP -FFT:D C & G N D , 10 avg.; P reA m p:x100, low noise , 2H P @ 0,03H z; U _DC =-6,5V
Q09/2001
Intensity Noise Control - Out of loop
10 0 10 1 10 2 10 3 10 4 10 5
frequency (H z)
10-9
10 -8
10 -7
10 -6
10 -5
10 -4R
IN(1
/H
z)
free runn ing, in j.lockout o f loop in tno iseanalyzer no ise @ C H 1 range 3 ,98 V pk
10.08.01; HP -FFT: DC &G N D , 10 avg.; PreAm p: x100, low no ise, 2HP @ 0,03H z; U _D C =-4,6 V
