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A Backscatter Tolerant Squeezer for Future Generation Gravitational Wave Detectors

A Backscatter Tolerant Squeezer for Future Generation Gravitational Wave Detectors. Michael Stefszky , Sheon Chua, Conor Mow-Lowry, Sheila Dwyer, Ben Buchler, Ping Koy Lam, Daniel Shaddock, and David McClelland Centre for Gravitational Physics at the Australian National University

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A Backscatter Tolerant Squeezer for Future Generation Gravitational Wave Detectors

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  1. A Backscatter Tolerant Squeezer for Future Generation Gravitational Wave Detectors Michael Stefszky, Sheon Chua, Conor Mow-Lowry, Sheila Dwyer, Ben Buchler, Ping Koy Lam, Daniel Shaddock, and David McClelland Centre for Gravitational Physics at the Australian National University LIGO DCC: G1100728

  2. The Story • Aim to develop a backscatter tolerant squeezer for future gravitational wave detectors. • Design requirements were met at end of last year • This squeezer is to be tested in the next few months in LIGO Hannford. Michael Stefszky Amaldi9 Cardiff 2011

  3. Squeezing results Michael Stefszky Amaldi9 Cardiff 2011

  4. Phase jitter and squeezing • RMS phase noise becomes broadband quantum noise • Similar effect to loss but it is exacerbated by impure squeezing • Jitter at any frequency degrades squeezing at all frequencies Michael Stefszky Amaldi9 Cardiff 2011

  5. Phase jitter and squeezing • RMS phase noise becomes broadband quantum noise • Similar effect to loss but it is exacerbated by impure squeezing • Jitter at any frequency degrades squeezing at all frequencies Michael Stefszky Amaldi9 Cardiff 2011

  6. Phase jitter and squeezing • RMS phase noise becomes broadband quantum noise • Similar effect to loss but it is exacerbated by impure squeezing • Jitter at any frequency degrades squeezing at all frequencies Michael Stefszky Amaldi9 Cardiff 2011

  7. Phase jitter and squeezing • RMS phase noise becomes broadband quantum noise • Similar effect to loss but it is exacerbated by impure squeezing • Jitter at any frequency degrades squeezing at all frequencies Michael Stefszky Amaldi9 Cardiff 2011

  8. Phase jitter and squeezing • RMS phase noise becomes broadband quantum noise • Similar effect to loss but it is exacerbated by impure squeezing • Jitter at any frequency degrades squeezing at all frequencies Michael Stefszky Amaldi9 Cardiff 2011

  9. The solution: A Box. Michael Stefszky Amaldi9 Cardiff 2011

  10. The solution: A Box. Michael Stefszky Amaldi9 Cardiff 2011

  11. The solution: A Box. Michael Stefszky Amaldi9 Cardiff 2011

  12. Parasitic interferometers • Scatter which propagates in the original beam path in the (0,0) mode interferometrically couples in phase fluctuations from mirror motion and air currents. Michael Stefszky Amaldi9 Cardiff 2011

  13. Parasitic interferometers • Scatter which propagates in the original beam path in the (0,0) mode interferometrically couples in phase fluctuations from mirror motion and air currents. Michael Stefszky Amaldi9 Cardiff 2011

  14. Scatter presence test • By sweeping the phase of a parasitic interferometer with a PZT, the phase noise can be moved out of band. • This technique can be used to diagnose the presence of scattered light. H. Lück et al.,J. Opt. A: Pure Appl. Opt.10 085004 (2008) Michael Stefszky Amaldi9 Cardiff 2011

  15. Scatter presence test • By sweeping the phase of a parasitic interferometer with a PZT, the phase noise can be moved out of band. • This technique can be used to diagnose the presence of scattered light. H. Lück et al.,J. Opt. A: Pure Appl. Opt.10 085004 (2008) Michael Stefszky Amaldi9 Cardiff 2011

  16. Shot noise with scatter shifting Following an optical change, scattered light noise was much higher. This was used as an opportunity to test the scatter mitigation technique. Michael Stefszky Amaldi9 Cardiff 2011

  17. The solution: Irises, Dumps and Baffles Michael Stefszky Amaldi9 Cardiff 2011

  18. The solution: Irises, Dumps and Baffles Michael Stefszky Amaldi9 Cardiff 2011

  19. Back-reflected light – recent work • One of the major issues when introducing a squeezer into a gravitational wave detector is the back reflected light from the detection scheme Conor Mow-Lowry GWADW Elba 2011

  20. Back-reflected light • One of the major issues when introducing a squeezer into a gravitational wave detector is the back reflected light from the detection scheme Conor Mow-Lowry GWADW Elba 2011

  21. Travelling-wave isolation • The travelling wave OPO provides isolation for back-reflected light from an interferometer. Michael Stefszky Amaldi9 Cardiff 2011

  22. Travelling-wave isolation • The travelling wave OPO provides isolation for back-reflected light from an interferometer. Michael Stefszky Amaldi9 Cardiff 2011

  23. Travelling-wave isolation • The travelling wave OPO provides isolation for back-reflected light from an interferometer. Michael Stefszky Amaldi9 Cardiff 2011

  24. Travelling-wave isolation • The travelling wave OPO provides isolation for back-reflected light from an interferometer. Michael Stefszky Amaldi9 Cardiff 2011

  25. Travelling-wave isolation • The travelling wave OPO provides isolation for back-reflected light from an interferometer. Michael Stefszky Amaldi9 Cardiff 2011

  26. Travelling-wave isolation • The travelling wave OPO provides isolation for back-reflected light from an interferometer. Michael Stefszky Amaldi9 Cardiff 2011

  27. Travelling-wave isolation • The travelling wave OPO provides isolation for back-reflected light from an interferometer. Michael Stefszky Amaldi9 Cardiff 2011

  28. Travelling-wave isolation • The travelling wave OPO provides isolation for back-reflected light from an interferometer. Michael Stefszky Amaldi9 Cardiff 2011

  29. Travelling-wave isolation Interfering the very low power back-reflected beam with the homodyne local oscillator. The resulting retro-reflectivity is 2.3e-5, or 46 dB of isolation. Michael Stefszky Amaldi9 Cardiff 2011

  30. Conclusions • We have seen squeezing with a travelling wave OPO which is: • Spectrally flat • Stable over 90 minutes • Large in magnitude and quite pure • RMS phase noise and scatter were our main enemies • There are improvements to be made to the detection chain which should result in 9+ dB of squeezing with the current OPO. • Squeezer soon to be tested in LIGO Hannford! Michael Stefszky Amaldi9 Cardiff 2011

  31. Michael Stefszky Amaldi9 Cardiff 2011

  32. Squeezing at 500 Hz Michael Stefszky Amaldi9 Cardiff 2011

  33. Bow-Tie Parameters • Cavity Length: 28cm • Finesse: 40 @ 1064nm, 17 @ 532nm • FSR: 1GHz • Threshold: Approx. 90mW • Escape Efficiency: Approx. 95% • Waist: 34um @ 1064nm • Input Coupler R: 70%@532nm, 87.5%@1064nm

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