Transcript nsf - Physics

Input Optics Definition, Function
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The input optics (IO) conditions light from the prestabilized laser (PSL) for injection into the main
interferometer
Specific functions
» modulation for RF sideband generation
» Mode cleaning of dynamic laser pointing fluctuations; intermediate
frequency and intensity stabilization
» Power control into interferometer
» Mode matching into interferometer cavities
» Optical isolation of the PSL and distribution of light for length and
alignment sensing and control
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Input Optics Conceptual Design
MC Length and
Alignm ent Sensing Pds
IFO Control
to ISC
ISC
Faraday
Isolator
MC ASC
Ac tuation
PSL
MC
Mode Matc hing
Telesc ope
RF
Modulation
PSL
Intensity
Stabilization
Mode Matc hing
Telesc ope
Steering
Mirrors
COC
Power Ac tive
Control Jitter
Suppression
Mode
Cleaner
MC Length
Ac tuation
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Input optics heritage
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Advanced LIGO IO evolves from current LIGO IO
» No major changes in AdL IO conceptual design
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Contiguity of IO team from current LIGO IO
» Univ. of Florida assumes primary responsibility (as in current LIGO)
» IO technical leaders same as in LIGO
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In terms of R&D, most progressed of Advanced LIGO
subsystems
» Relatively low technical risk
» Conceptual Design and Design Requirements completed May 2002
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Major R&D
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Electro-optic modulators: materials, architecture
Faraday Isolators: thermal lensing, depolarization, dynamics
Adaptive mode matching
Mode cleaner thermal and noise modeling
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Current Progress I
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Modulators
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» RTP: excellent thermal properties
and nonlinear properties
» RTP-based transverse modulator
prototype tested
– temperature-stabilized
– no thermal lensing observed at
50 W powers
Isolators
»
Demonstration of fully compensated
TGG-based isolator
» 45 dB isolation
» Negligible thermal lensing
Thermal
compensation
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No thermal
compensation
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Current Progress II
Model
Performance
Preliminary
Experiment
Adaptive Mode Matching
» Preserves modal content
532 nm
1064 nm
10
1.0
8
0.9
TEM00 Mode Content
» in situ adjustment of mode
matched based on laser/radiative
heating
» Ratio of ‘writing’ beam to
‘reading’ beam waist large
Effective Radius of Curvature (m)
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6
4
TEM00 (original basis)
TEM00 (new basis)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0
1
2
0
0
2
3
4
5
Incident Writing Beam Power
1
2
3
4
5
Incident Writing Beam Power (W)
Schott OG515
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Technical
Challenges/Opportunities
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Challenges:
» High power poses problems to IO optical components
– Thermal lensing, thermally-induced depolarization, long term
degradation
– Primarily affects electro-optic modulators
– Sideband amplitude stability
– challenging for DC readout; beyond state-of-the-art for RF oscillators
» Excess laser jitter may require active suppression
– MC technical radiation pressure at requirement limit for required
frequency noise
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Opportunities
» Novel adaptive optics
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R&D Plans for 2004
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Upgrade to 100 W laser testing
» LIGO Livingston High Power Test Lab (underway)
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EOM prototype testing
» RF amplitude modulation, amplitude modulation from parasitic nonlinear
processes
» Frequency stability (at limit of RF oscillator)
» Long term laser exposure and damage testing (100 W powers)
» Contingency modulation architectures if required
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Mode cleaner R&D
» MELODY model of thermal effects (carrier, sidebands), potential
astigmatism (mostly done)
» Better understanding of beam jitter in PSL; if necessary, examination of
possibility of second mode cleaner
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R&D Plans for 2004 (cont’d)
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Faraday isolation
» Investigate dynamic effects due to loss of lock and rapid thermal loading
» Trade study of optimal commercial components (wave plates, polarizers,
TGG)
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Interferometer mode-matching
» Prototype thermal adaptive telescope in vacuum
» Preliminary Advanced LIGO telescope design; MELODY modeling of
performance under various powers
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System interface issues
» In-vacuum layout (underway)
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Schedule
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Design phase
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Design Requirements and Conceptual Design: May 2002 (completed)
Preliminary Design Phase: April 2005
Final Design: November 2007
Milestones
– Design LASTI mode cleaner and ancillary input optics: November 2002 (completed)
– Deliver prototype modulators and isolators to Gingin High Power Test Facility: June
2004
– Deliver LASTI mode cleaner and ancillary optics: January 2005
– Deliver prototype modulators and isolators to LASTI: January 2006
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Fabrication and assembly phase
» Major optics procurement (all interferometers): August 2006 – August 2009
» Input optics installation
– Interferometer 1: thru August 2008
– Interferometer 2: thru February 2009
– Interferometer 3: thru September 2009
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IO Team
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IO Manager: D. Reitze (Univ. Florida)
LIGO Lab Liaison: P. King (CIT)
IO Team
» Univ. of Florida
– R. Amin, K. Franzen, G. Mueller, M. Rakhmanov, D. Tanner, V. Quetschke, L. Zhang
» Institute of Applied Physics (Nizhny Novgorod, Russia)
– E. Khazanov, A. Malshakov, A. Shakin, A. Sergeev
» LIGO Lab
– P. King, R. Savage
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