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Advanced VIRGO Input optics LIGO-G070361-00-Z

Advanced VIRGO Input optics LIGO-G070361-00-Z. The Advanced Virgo injection system. Advanced VIRGO: in 2011 VIRGO should be ready to be upgraded to a detector with about 200 W input power 200 W Laser source: two options are open (see Nary’s talk): Solid State Laser source (SSL)

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Advanced VIRGO Input optics LIGO-G070361-00-Z

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  1. Advanced VIRGO Input optics LIGO-G070361-00-Z

  2. The Advanced Virgo injection system • Advanced VIRGO: in 2011 VIRGO should be ready to be upgraded to a detector with about 200 W input power • 200 W Laser source: two options are open (see Nary’s talk): • Solid State Laser source (SSL) • Fibre Laser (FL) source • The layout of the optics downstream of the laser has not been decided. Open options are: • In-air elements (Faraday, EOM, mirrors, waveplates, polarizers, …) • Suspended resonant input mode cleaner • In vacuum suspended optics (Faraday, polarizers) • Matching telescope • Photonic fibre input mode cleaner • Integrated fibre elements In any case: components withstanding 200 W

  3. Standard solution (LIGO) RESONANT SUSPENDED INPUT MODE CLEANER SUSPENDED OPTICS (FI) AND INPUT TELESCOPE 200 W SSL LASER IN AIR HP INPUT OPTICS FI FI EOM

  4. Possible fibre alternative Possible fibre solution: • Fibre integrated components (EOM, FI, …) • Fibre IMC • In vacuum Faraday isolator • Matching telescope

  5. All fibre solution SUSPENDED OPTICS AND INPUT TELESCOPE HP INTEGRATED FIBRE INPUT OPTICS PHOTONIC FIBRE INPUT MODE CLEANER 200 W FIBRE LASER EOM FI FI

  6. Present advanced VIRGO reference solution LIGO: • Solid State Laser source • In-air components • Suspended resonant IMC • In vacuum Faraday isolator and suspended optics • Matching telescope • Lots of R&D already done

  7. VIRGO present activity • A program for developing High Power Input Optical components has been funded (February 2007): • All what is necessary for setting up the HP power source is being purchased: • HP Ytterbium laser (IPG 200 W) • Optics • Beam analyser • Detectors • Cavities • Clean air, beam dumps • Vacuum chamber • … • First tests: • Tests on DKDP samples could start in Fall Simulation and tests of thermal effects in Faraday isolators are being performed (see Slim’s talk) • Even if Advanced VIRGO polarizers reference solution is likely calcite, tests on Brewster polarizers (General Optics substrates and Lyon coatings) for VIRGO+ will start in fall 2007

  8. HP- IO components for Advanced Virgo l/2 HP PUMP SINGLE MODE PROBE POL HP power meter CCD Test cavity ACQUISITION Beam Analyser Beam Analyser Phd Phd

  9. HP- IO components for Advanced Virgo l/2 HP PUMP l/2 SINGLE MODE PROBE EOM POL HP power meter CCD Test cavity ACQUISITION Beam Analyser Beam Analyser Phd Phd

  10. EOM • In VIRGO+ EOM made of KTP crystal will be used • Same as present VIRGO • Thermal focal length (about 30 m) corrected by the in air tuning telescope • Reference solution: Advanced LIGO EOM: • RTP EOM crystal: • About 10 times lower absorption (0.005 m-1 vs 0.05 m-1) • Lower dnz/dT • Higher damage threshold • wedged (about 3°) EOM crystals • We will in any case perform tests on KTP EOM (already for VIRGO+)

  11. HP- IO components for Advanced Virgo l/2 HP PUMP l/2 SINGLE MODE PROBE Faraday POL DKDP HP power meter CCD Test cavity ACQUISITION Beam Analyser Beam Analyser Phd Phd

  12. Faraday isolator • An in-vacuum Faraday isolator will be used even with a fibre IMC • Good experience already acquired in Virgo: • Thermal lensing • Thermal effects on isolation • Many things understood ad a lot of simulation performed • Results can be compared with those of LIGO • Ready to start soon high power in-vacuum tests (Slim’s talk) • Reference solution for Advanced Virgo: Advanced LIGO Faraday Isolator

  13. Fibre solution Fibred components: (like integrated fibred EOM, FI) Apparently more advantageous: • Reliability • Alignment • Neither acoustic nor seismic noise • High power • Telecom tested solutions • Easily integrated with a fibred input mode cleaner • … But: • More experience needed soon • Very short time to make high power tests

  14. Possible adaptation for HP-IO fibred components l/2 HP PUMP SINGLE MODE PROBE Fibred components POL HP power meter CCD Test cavity ACQUISITION Beam Analyser Beam Analyser Phd Phd

  15. Working program At the same time we need: • Start requirements computation (EOM, IMC, telescopes, stabilization, …) • Start simulation and design of a possible resonant IMC • Start simulation and design of a possible matching telescope • Take advantage from LIGO R&D • Perform our own R&D and develope experience

  16. Input Optics (Faraday, EOM, Polarizers, …) Requirements: • Faraday (in air and in vacuum) • Level of power impinging on them • Level of optical isolation • Insertion loss allowed • Beam distorsion allowed • Compensation (lensing, isolation) • EOM: • Minimum modulation depth • Stability of sidebands • Level of power impinging on them • Polarizers, mirrors, splitters (scattering issues) • How things will change depending on the choices for the ITF (for example if there will be DC detection).

  17. Input Mode Cleaner Requirements: Which are the different options open • Suspended • Fibre In case of suspended IMC: • Length, Finesse, transmission, use of dihedron • Frequency pole for HF noise • Scattered light on the mirrors and on their support, • Seismic isolation of the mirrors • Filtering

  18. Input/output telescopes Requirements: • Which are the different options: • Long, short • Standard lenses • Parabolic, off-axis • Adaptive matching • Stability, Matching, Insertion loss by aberrations • Seismic isolation • Scattering: maximum reflection by AR coatings • Depending on: • Different possible IMC • ITF configuation

  19. What is being done • In-air HP-IO components: Activity started: EGO, Pisa, Naples • In vacuum suspended optics: Activity started: EGO, Pisa, Naples • Integrated fibre elements: To be decided: Possible within the EGO, Pisa, Naples R&D (coordinated with NIce activity) • Suspended resonant IMC: Very little action taken • Matching telescope No action taken

  20. WG2 involved people • 21 People included in the WG2 mailing list • Work effectively performed by only a few of them • All of them are also involved in the Virgo Commissioning and/or in the Virgo+ ugrades • More collaboration with WG1 is needed: very important for defining requirements • Injection system configuration: not yet assessed • Manpower, at least up to now, is not sufficient • After the start of the Science Run more time/people will be available

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