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Input Optics Definition, Function

Input Optics Definition, Function. The input optics (IO) conditions light from the pre-stabilized laser (PSL) for injection into the main interferometer Specific functions modulation for RF sideband generation

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Input Optics Definition, Function

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  1. Input Optics Definition, Function • The input optics (IO) conditions light from the pre-stabilized 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 LIGO R&D

  2. Input Optics Conceptual Design LIGO R&D

  3. Input optics heritage • Advanced LIGO IO evolves from current LIGO IO • No major changes in AdL IO conceptual design • 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 • In terms of R&D, most progressed of Advanced LIGO subsystems • Relatively low technical risk • Conceptual Design and Design Requirements completed May 2002 • Major R&D • Electro-optic modulators: materials, architecture • Faraday Isolators: thermal lensing, depolarization, dynamics • Adaptive mode matching • Mode cleaner thermal and noise modeling LIGO R&D

  4. Current Progress I • Modulators • 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 No thermal compensation LIGO R&D

  5. Current Progress II Preliminary Experiment 532 nm 1064 nm Schott OG515 Model Performance • Adaptive Mode Matching • in situ adjustment of mode matched based on laser/radiative heating • Ratio of ‘writing’ beam to ‘reading’ beam waist large • Preserves modal content LIGO R&D

  6. Technical Challenges/Opportunities • 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 • Opportunities • Novel adaptive optics LIGO R&D

  7. R&D Plans for 2004 • Upgrade to 100 W laser testing • LIGO Livingston High Power Test Lab (underway) • 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 • 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 LIGO R&D

  8. R&D Plans for 2004 (cont’d) • Faraday isolation • Investigate dynamic effects due to loss of lock and rapid thermal loading • Trade study of optimal commercial components (wave plates, polarizers, TGG) • Interferometer mode-matching • Prototype thermal adaptive telescope in vacuum • Preliminary Advanced LIGO telescope design; MELODY modeling of performance under various powers • System interface issues • In-vacuum layout (underway) LIGO R&D

  9. Schedule • Design phase • 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 • 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 LIGO R&D

  10. IO Team • 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 LIGO R&D

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