1. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 1 Advanced VIRGO Input optics LIGO-G070361-00-Z

2. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 2 The Advanced Virgo injection system l Advanced VIRGO: in 2011 VIRGO should be ready to be upgraded to a detector with about 200 W input power l 200 W Laser source: two options are open (see Nary’s talk):  Solid State Laser source (SSL)  Fibre Laser (FL) source l 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. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 3 Standard solution (LIGO) 200 W SSL LASER IN AIR HP INPUT OPTICS RESONANT SUSPENDED INPUT MODE CLEANER SUSPENDED OPTICS (FI) AND INPUT TELESCOPE EOM FIFI

4. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 4 Possible fibre alternative Possible fibre solution :  Fibre integrated components (EOM, FI, …)  Fibre IMC  In vacuum Faraday isolator  Matching telescope

5. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 5 All fibre solution 200 W FIBRE LASER HP INTEGRATED FIBRE INPUT OPTICS PHOTONIC FIBRE INPUT MODE CLEANER SUSPENDED OPTICS AND INPUT TELESCOPE FI EOM FI

6. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 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. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 7 VIRGO present activity l A program for developing High Power Input Optical components has been funded (February 2007): l 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  … l 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. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 8 HP- IO components for Advanced Virgo SINGLE MODE PROBE HP PUMP /2 /2 POL HP power meter Phd BeamAnalyser CCD Test cavity ACQUISITION BeamAnalyser Phd

9. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 9 HP- IO components for Advanced Virgo SINGLE MODE PROBE HP PUMP /2 /2 POL HP power meter Phd BeamAnalyser CCD Test cavity ACQUISITION BeamAnalyser Phd /2 /2 EOM

10. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 10 EOM l 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 l Reference solution: Advanced LIGO EOM:  RTP EOM crystal: –About 10 times lower absorption (0.005 m -1 vs 0.05 m -1 ) –Lower dn z /dT –Higher damage threshold –wedged (about 3°) EOM crystals l We will in any case perform tests on KTP EOM (already for VIRGO+)

11. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 11 HP- IO components for Advanced Virgo SINGLE MODE PROBE HP PUMP /2 /2 POL HP power meter Phd BeamAnalyser CCD Test cavity ACQUISITION BeamAnalyser Phd /2 /2 DKDP Faraday

12. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 12 Faraday isolator l An in-vacuum Faraday isolator will be used even with a fibre IMC l Good experience already acquired in Virgo:  Thermal lensing  Thermal effects on isolation l Many things understood ad a lot of simulation performed l Results can be compared with those of LIGO l Ready to start soon high power in-vacuum tests (Slim’s talk) l Reference solution for Advanced Virgo: Advanced LIGO Faraday Isolator

13. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 13 Fibre solution Fibred components: (like integrated fibred EOM, FI) Apparently more advantageous: l Reliability l Alignment l Neither acoustic nor seismic noise l High power l Telecom tested solutions l Easily integrated with a fibred input mode cleaner l … But : l More experience needed soon l Very short time to make high power tests

14. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 14 Possible adaptation for HP-IO fibred components SINGLE MODE PROBE HP PUMP /2 /2 POL HP power meter Phd BeamAnalyser CCD Test cavity ACQUISITION BeamAnalyser Phd Fibredcomponents

15. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 15 Working program 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 At the same time we need:

16. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 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. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 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. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 18 Input/output telescopes Requirements: l Which are the different options:  Long, short  Standard lenses  Parabolic, off-axis  Adaptive matching l Stability, Matching, Insertion loss by aberrations l Seismic isolation l Scattering: maximum reflection by AR coatings l Depending on:  Different possible IMC  ITF configuation

19. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 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 telescopeNo action taken

20. Paolo La Penna Injection optics for Advanced VirgoLSC/VIRGO joint meeting, Cascina, 25/05/2006 20 WG2 involved people l 21 People included in the WG2 mailing list l Work effectively performed by only a few of them l All of them are also involved in the Virgo Commissioning and/or in the Virgo+ ugrades l More collaboration with WG1 is needed: very important for defining requirements l Injection system configuration: not yet assessed l Manpower, at least up to now, is not sufficient l After the start of the Science Run more time/people will be available