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Caltech 40m Lab Update: LSC Meeting Baton Rouge Mar. 21, 2007

Update on the Caltech 40m interferometer project presented at the LSC meeting in Baton Rouge. Focus on RSE interferometer, DC readout, and noise characterization for AdLIGO and future upgrades.

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Caltech 40m Lab Update: LSC Meeting Baton Rouge Mar. 21, 2007

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  1. Caltech 40m Lab Update LSC Meeting Baton Rouge Mar 21, 2007 Robert Ward, Caltech and the 40m team: Rana Adhikari, Benjamin Abbott, Rich Abbott, Rolf Bork, Tobin Fricke, Valery Frolov, Keisuke Goda, Jay Heefner, Alexander Ivanov, Osamu Miyakawa, Kirk McKenzie, Royal Reinecke, Bram Slagmolen, Michael Smith, Robert Taylor, Stephen Vass, Sam Waldman, and Alan Weinstein LSC meeting at Baton Rouge, March 2007

  2. Caltech 40 meter prototype interferometer(mini-LIGO) Objectives • Develop lock acquisition procedure of detuned Resonant Sideband Extraction (RSE) interferometer, as close as possible to AdLIGO optical design Test/Characterize LSC scheme Develop DC readout scheme Characterize noise mechanisms Test QND techniques Develop/Test ASC scheme Testbed for AdLIGOcontrols technologies Prototyping will yield crucial information about how to build and run AdLIGO (and eLIGO). LSC meeting at Baton Rouge, March 2007

  3. AdLIGO: Detuned RSE We can operate the 40m in multiple configurations, with various control schemes. Depicted here is the 40m version of the baseline AdLIGO optical configuration ITMy 166MHz 1900W ITMx 13m MC BS SP166 33MHz F ~ 1200 PRM Miyakawa et. al., PRD 74 022001 (2006) LIGO-P060007-00-R PO DDM SRM SP DDM REFL AP DDM AP166 DARM LSC meeting at Baton Rouge, March 2007

  4. QND: Squeezing Enhanced SRMI misalign ETMs and PRM to get a signal-recycled michelson ITMy ITMx BS SQUEEZER PRM SRM SP 166 Homodyne Detector LSC meeting at Baton Rouge, March 2007

  5. eLIGO: Power Recycled Fabry Perot Michelson misalign signal-recycling mirror to get a lossy LIGO- like configuration. This is as close as we can get to the eLIGO configuration ITMy ITMx 13m MC BS SP166 33MHz PRM SRM DARM DC SP 33 REFL AP 33 OMC DARM RF LSC meeting at Baton Rouge, March 2007

  6. Better Signal Detection:Output Mode Cleaner Basic Motivations • Limited by photodetector saturations; OMC removes most of the junk light • Removing the junk light reduces shot noise • DC Readout (AdvLIGO baseline) has technical noise benefits: • Optical gain increase (field overlap) • RF Oscillator phase noise (significant at ~few kHz) • Laser frequency noise (close to limiting) • Past OMC testing on H1 showed benefits, but was ~300x too noisy • Critical for any high power operations (H2 only uses 2.5 W of laser power) GEO / H1 LSC meeting at Baton Rouge, March 2007 Caltech 40m

  7. DC Readout components • Output Mode cleaner • Four-mirror design, 48 cm round-trip length • Finesse 210; transmission 92%; loss 0.1% round trip • PZT length actuation; dither-lock at ~12 kHz • Two in-vac PZT tip-tilt steering mirrors • Steer the IFO output into the output mode cleaner • Mode-matching telescope (picomotor focus control) • In-Vacuum Photodetector • 2mm InGaAs diodes, with an amplifier/whitening circuit in a can. • AdLIGO-style PCIX system for digital control (CDS) • Front-end code auto-generated from simulink drawing (Borkspace) • 32 kHz real time control (Rest of 40m is 16kHz) • Interfaced to existing VME-based RFM network LSC meeting at Baton Rouge, March 2007

  8. ELECTRONICS PD MMT1 OMC Tip/Tilt RF PICKOFF MMT2 Squeezer Pickoff OMC/DC Readout Installation • DC Readout Beamline Installed September 2006 • Electronics+ Software installed October 2006 LSC meeting at Baton Rouge, March 2007

  9. OMC: It cleans the modes AS PORT Before OMC OMC Transmitted LSC meeting at Baton Rouge, March 2007

  10. OMC Mode Scan (PRFPMI) Dark port HOM content Carrier m+n = 2 33MHz (f1) OMC TRANSMISSION m+n =3 m+n =4 m+n = 1 LSC meeting at Baton Rouge, March 2007

  11. DC READOUT COMMISIONING • most hardware installed, tested • All PZTs, picos, PDs work as expected. Still QPDs to go. • All software installed, tested • PCIX controls, interfaced successfully with current LIGO-like VME ISC control system. This result is important for eLIGO. • OMC Controls version 1.0 • All digital demodulation, without using an AWG • OMC Length dither locked (dither freq 12kHz, UGF 100Hz) • dither amplitude ~ 5 pm • OMC Alignment Sensing & Control • dither locked (two tip/tilts, 4 DOFs) • dither freqs ~4 - 7 kHz • servo bandwidth: 2@20Hz, 2@subHz • dither amplitude ~ 5 urad (?) LSC meeting at Baton Rouge, March 2007

  12. RF vs DC: Displacement Noise DARM offset ~35pm eLIGO configuration (PRFPMI) Developed a new PRFPMI lock acquisition technique along the way. LSC meeting at Baton Rouge, March 2007

  13. NEXT for DC Readout • Optimization of auxilliary loops • Noise-based optimization of OMC controls • A little bit of noise hunting • Measure laser noise transfer functions, compare with models • Frequency noise • Intensity noise • Oscillator phase noise • Map out optimal DARM offset, compare with modeling. • DC Readout with SIGNAL RECYCLING LSC meeting at Baton Rouge, March 2007

  14. New Digital Controls Systems BorkSpace front-end code generation system Just type “make” then build MEDM screens and you’re ready. LSC meeting at Baton Rouge, March 2007

  15. Alignment Sensing & Stabilization • Dither each suspension in pitch & yaw, demod at various signal ports. No AWG. • ULB alignment and spot centering. LSC meeting at Baton Rouge, March 2007

  16. Digital Lock-in LSC meeting at Baton Rouge, March 2007

  17. Summary & Future plans • DC Readout in an eLIGO like configuration is in full swing. Quantitative measurements & comparisons with RF schemes coming (very) soon->Noise budget. • DC Readout in an AdLIGO style IFO coming soon. • Finish commissioning IFO dither alignment system. • Possible integration of vacuum squeezing with OMC/DC Readout in the medium term. • New AdLIGO – style CDS infrastructure working well, and meshing with current LIGO – style CDS infrastructure. • We have ~100 ppm loss per test mass. Plan to do some tests to investigate/mitigate this in the near term. LSC meeting at Baton Rouge, March 2007

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