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ET filter cavities for third generation detectors

ET filter cavities for third generation detectors. Keiko Kokeyama Andre Thüring. Contents. Introduction of Filter cavities for ET Part1. Filter-cavity-length requirement - Frequency dependant squeezing - Filter cavity length and the resulting squeezing level

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ET filter cavities for third generation detectors

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  1. ET filter cavities for third generation detectors Keiko Kokeyama Andre Thüring

  2. Contents • Introduction of Filter cavities for ET • Part1. Filter-cavity-length requirement • - Frequency dependant squeezing • - Filter cavity length and the resulting squeezing level • Part2. Layout requirement from the scattering light analysis • Summary K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  3. Contents • Introduction of Filter cavities for ET • Part1. Filter-cavity-length requirement • - Frequency dependant squeezing • - Filter cavity length and the resulting squeezing level • Part2. Layout requirement from the scattering light analysis • Summary K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  4. Design sensitivity for ET-C Letsfocus on the ET-C LF part. • ET-C : Xylophone consists of • ET-LF and ET-HF • ET-C LF • Low frequency part of the xylophone • Detuned RSE • Cryogenic • Silicon test mass & 1550nm laser • HG00 mode S. Hild et al. CQG 27 (2010) 015003 1/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  5. To reach the targeted sensitivity, we have to utilize squeezed states of light We dream of a broadband QN-reduction by 10dB A broadband quantum noise reduction requires the frequency dependent squeezing, therefore filter cavities are necessary 2/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  6. Contents • Introduction of Filter cavities for ET • Part1. Filter-cavity-length requirement • - Frequency dependant squeezing • - Filter cavity length and the resulting squeezing level • Part2. Layout requirement from the scattering light analysis • Summary K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  7. Contents • Introduction of Filter cavities for ET • Part1. Filter-cavity-length requirement • - Frequency dependant squeezing • - Filter cavity length and the resulting squeezing level • Part2. Layout requirement from the scattering light analysis • Summary K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  8. X2 X2 X1 X1 Quantum noise in a Michelson interferometer X2 X1 Quantum noise reduction with squeezed light Filter cavities can optimize the squessing angles 3/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  9. ET-C LF bases on detuned signal-recycling Two filter cavities are required for an optimum generation of frequency dependent squeezing Optical spring resonance Opticalresonance In this talk we consider the two input filter cavities 4/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  10. Contents • Introduction of Filter cavities for ET • Part1. Filter-cavity-length requirement • - Frequency dependant squeezing • - Filter cavity length and the resulting squeezing level • Part2. Layout requirement from the scattering light analysis • Summary K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  11. Requirementsdefinedbytheinterferometerset-up: Thebandwidths and detunings of thefiltercavities Whatwecanchoose The lengths of the filter cavities ...And the optical layout (Part2) Limitations Infrastructure, opticalloss (e.g. scattering) , phasenoise, ... 5/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  12. Degrading of squeezing due to optical loss At everyopen (lossy) portvacuumnoisecouples in coupling mirror A cavity reflectance R<1 means loss . The degrading of squeezing is then frequency dependent 6/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  13. The impact of intra-cavity loss The filter‘s coupling mirror reflectance Rc needs to be chosen with respect to 1. therequiredbandwidthg accountingfor 2. theround-triplosslRT 3. a givenlengthL Thereexists a lowerlimitLmin. For L < Lminthefiltercavityisunder-coupled and thecompensation of thephase-space rotation fails! 7/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  14. The impact of shortening the cavity length If L < Lmin ~ 1136 m thefilterisunder-coupled and thefilteringdoesnotwork Examplefor ET-C LF detuning = 7.1 Hz 100 ppmround-triploss, bandwidth = 2.1 Hz For L < 568m Rc needs to be >1 The filter cavity must be as long as possible for ET-LF 8/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  15. Narrow bandwidths filter are more challenging Assumptions: L = 10 km, 100 ppmround-triploss, Detuning = 2x bandwidth Filter cavities with a bandwidth greater than 10 Hz are comparatively easy to realize 9/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  16. Exemplary considerations for ET-C LF Filter I: g = 2.1 Hz fres = 7.1 Hz Filter II: g = 12.4 Hz fres = 25.1 Hz 15dB squeezing 100ppm RT - loss 7% propagationloss Filter I: L = 2 km F = 17845 Rc = 99.9748% Filter II: L = 2 km F = 3022 Rc = 99.8023% Filter I: L = 5 km F = 7138 Rc = 99.9220% Filter II: L = 5 km F = 1209 Rc = 99.4915% Filter I: L = 10 km F = 3569 Rc = 99.8341% Filter II: L = 10 km F = 604 Rc = 98.9757% 10/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  17. Contents • Introduction of Filter cavities for ET • Part1. Filter-cavity-length requirement • - Frequency dependant squeezing • - Filter cavity length and the resulting squeezing level • Part2. Layout requirement from the scattering light analysis • Summary K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  18. Stray light analysis for four designs Linear Triangular - Conventional Rectangular Bow-tie Which design is suitable for ET cavities from the point of view of the loss due to stray lights? 11/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  19. Scattering Angle and Fields Linear Triangular Rectangular Bow-tie 12/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  20. Scattering Field Category 13/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  21. Scattering Field Category 13/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  22. #1 Counter-Propagating, Small f0,f~0 Coupling factor • C1 =A<ETEM00•m(x,y) •E*TEM00> 14/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  23. Scattering Field Category 15/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  24. #2 Counter-Propagating, Large f0,f=0 Coupling factor • C2= A<ETEM00•m(x,y) •E*TEM00> 15/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  25. Scattering Field Category 16/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  26. #3 Counter-Propagating, Large f (at 2nd scat) #4 Counter-Propagating, Small f (at 2nd scat) • C3=<ETEM00tail •E*TEM00> • C4 =<ESphe •E*TEM00> 16/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  27. Scattering Field Category 17/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  28. #5 Normal-Propagating, Large f (at 2nd scat) #6 Normal-Propagating, Small f (at 2nd scat) • C5=<ETEM00tail •E*#TEM00> • C6 =<ESphe •E*# TEM00> 17/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  29. -----= 18/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  30. Preliminary Results 19/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

  31. Summary • We have shown that the requirement of the filter-cavity length which can accomplish the necessary level of squeezing • We have evaluated the amount of scattered light from the geometry alone to select the cavity geometries for arm and filter cavities for ET. • As a next step coupling factors between each fields and the main beam should be calculated quantitatively so that total loss and coupling can be estimated. • At the same time the cavity geometries will be compared with respect to astigmatism, length & alignment control method 20/20 K. Kokeyamaand Andre Thüring 17 May 2010, GWADW

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