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M.Varvella Virgo LAL Orsay / LIGO CalTech

Time domain model for a dual-recycled interferometer. M.Varvella Virgo LAL Orsay / LIGO CalTech. Outline. Dual-recycled interferometer 40m IFO status collaboration Virgo LAL / LIGO Caltech: 40m/advLIGO simulation dual recycled 40m commissioning LIGO e2e simulation: Introduction to e2e

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M.Varvella Virgo LAL Orsay / LIGO CalTech

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  1. Time domain model for a dual-recycled interferometer M.Varvella Virgo LAL Orsay/LIGO CalTech Napoli, October 22, 2004

  2. Outline • Dual-recycled interferometer • 40m IFO status • collaboration Virgo LAL / LIGO Caltech: • 40m/advLIGO simulation • dual recycled 40m commissioning • LIGO e2e simulation: • Introduction to e2e • Mach-Zehnder • 40m/advLIGO • from 40m/advLIGO to upgraded Virgo Napoli, October 22, 2004

  3. Sensitivity With Signal Recycling Without Signal Recycling Cavities Power Recycling Mirror LASER Signal Recycling Mirror DUAL-RECYCLED INTERFEROMETER • 5 longitudinal d.o.f. to be controlled • Locking and Alignment problems • Control strategies better sensitivity in a narrow frequency band Napoli, October 22, 2004

  4. ETMy Ly ITMy lsy ETMx PRM Laser ly ITMx BS lx Lx lsx SRM PO SP AP Signal recycling:Experimental problems Common of arms Differential of arms Power recycling cavity Michelson Signal recycling cavity : L = (Lx Ly) / 2 : L =Lx Ly :l = (lx ly) / 2 : l =lx ly :ls = ( lsx lsy) / 2 Napoli, October 22, 2004

  5. Dual-recycled interferometer in the world Already installed: • 40m@ CalTech with Fabry-Perot cavities • GEO 600 @ Germany without Fabry-Perot cavities Note: 10m @ Glasgow has signal recycling cavity but it is not dual Not yet existing: • AdvLIGO @ United States with Fabry-Perot cavities • same configuration than 40m • upgraded Virgo ?! Napoli, October 22, 2004

  6. BS SRM PRM Bright port Dark port X arm ETMy Y arm ITMy PSL ETMx PRM ITMx BS MC SEM CalTech 40m Status • Four TMs and BS: installedSeptember, 2003 • FP Michelson lockedNovember 2003 • Power Recycling Mirror (PRM) , Signal Extraction Mirror (SRM) installedFebruary 2004 • Full alignment, FPMI re-locked after installation March 2004 • Discovery of SB-on-SB problem May 2004 • Construction/Commissioning of MZ June ~July 2004 • Lock of the IFO Central Part of IFO August 2004 Napoli, October 22, 2004

  7. ETMy 4km ITMy PRM ITMx BS 4km Carrier (Resonant on arms) SRM -f2 -f1 f1 f2 SIGNAL EXTRACTION for 40m/AdvLIGO Two modulations are used to separate high finesse, 4km long arm cavity signals fromCentral part (Michelson, PR, SR) signals. • Arm cavity signals are extracted from beat between carrier and f1 or f2. • Central part (Michelson, PR, SR) signals are extracted from beat between f1 and f2, not including arm cavity information. 40m advLIGO f1 = 33 MHz f2= 166 MHz f1 = 9 MHz f2= 180 MHz ETMx • Single demodulation • Arm information • Double demodulation • Central part information Napoli, October 22, 2004

  8. EOM1 EOM2 SIDEBANDS of SIDEBANDS Simulation Real world • Desire to control short degrees of freedom (MICH, PRC, SRC) using beats between RF sidebands only (f1±f2), no carrier, to be immune to large signals from arm cavities • Application of f1 and f2 using serial EOMs produces sidebands on sidebands, at (f1±f2), so that beats appear with carrier, corrupting signals for short dof’s. • After considering several solutions, EOMs in parallel via Mach-Zehnder interferometer have been installed. EOM = Electro-Optical-Modulator Napoli, October 22, 2004

  9. MACH-ZEHNDER on 40m PSL EOMs in series EOMs in parallel (Mach-Zehnder) • Control • Originally, using internal modulation with 33 MHz(f1)to lock MZ • Might need to turn down 33, 166 (f2) MHz during lock acquisition procedure; don’t want to lose MZ lock • Instead, put 29 MHz EOM (used for MC lock) into MZ east arm, and lock with that  now using 29MHz Napoli, October 22, 2004

  10. 40m IFO Plans for near future • Continue march towards lock acquisition of DRFPMI • Complete work on LSC photodetectors and electronics • Optimize dither-locking of MICH • Establish double-demod signals for PRC/SRC, and set demod phases • Lock central part (MICH/PRC/SEC) and transfer to final control config • Add arms to locked central part • Switch smoothly to DARM/CARM • Add common mode servo • Automate smooth lock acquisition procedure • Measure in-lock transfer functions. • Verify RSE and optical spring • Begin noise characterization • Operate at a different SRC tune? • Begin work towards DC detection • output mode cleaner • offset locking of arm • DC photodetector • noise characterization full lock acquired Napoli, October 22, 2004

  11. ETMy ITMy PSL ETMx PRM ITMx BS MC SEM Collaboration Virgo LAL - LIGO CalTech • e2e simulation for 40m/advLIGO • re-summation cavity formulation LIGO simulation group 40m IFO group 40m commissioning Napoli, October 22, 2004

  12. SIMULATION • First approach → e2e simulation • LIGO e2e simulations understanding • 40m/advLIGO model in progress • The same model for both the interferometers (same configurations); all the parameters are specified in macros to simplify the switch between configurations. • Long term goal: • Signal Recycling package for upgraded Virgo • Adaptation of the 40m/advLIGO model to Upgraded Virgo Napoli, October 22, 2004

  13. End-to-End (e2e) simulation • Time domain simulation written in C++ • simulating realistically with non linearity automatically included • Major physics components and tools relevant for LIGO • fields & optics, mechanics, digital and analog electronics, measured noise… • Flexible to design wide varieties of systems • from fast prototyping to full design • Easy development and maintenance • use of graphical front end written in JAVA for the system design • object orient design for easy addition of new physics • End to End simulation environment • Simulation programs - program to run • modeler : time series generator • modeler_freq : spectrum analyzer • Description files defining what to simulate - input files • Graphical Editor to create and edit description files - alfi - editor Napoli, October 22, 2004

  14. e2e Graphical Editor ALFI (AdLib Friendly Interface) Laser mirror mirror Photodiode propagator Photo diode Napoli, October 22, 2004

  15. e2e exampleFabry-Perot cavity dynamics 1 m / s ETMz = -10-8 + 10-6 t Resonant at Reflected Power Transmitted Power X 100 Power = 1 W, TITM=0.03, TETM=100ppm, Lcavity = 4000m Napoli, October 22, 2004

  16. Inputs and outputs in End-to-End • Description files - box files • what to simulate • use I/O primitives to read and write data • Macro definitions • all numerical values in box files can be written using symbolic names • Outputs • no built in analysis tools • time series • psd • spectrum analyzer Napoli, October 22, 2004

  17. e2e simulation: Double Fabry-Perot Cavity %* Alfi_Version 5.6.8 Add_Submodules { field_gen laser mirror2 mirror2_1 mirror2 mirror2_2 propagator Prop_I2E propagator Prop_E2I power_meter power_meter_8 xyz2clamp ETMMotion FUNC_1x1 ETMz sideband_gen sideband_gen_11 data_in data_in_12 f2k f2k_13 pd_demod pd_demod complex2reim complex2reim_15 mirror2 mirror2_0 propagator Prop_I2E_2 propagator Prop_E2I_2 } Settings laser { max_mode_order = -1 power = 1 %* GUI_Settings %* { %* Origin 48x156 %* } } ……….. graphical view .box program text view

  18. PMC trans PZT EOM2 To MC EOM1 EOM3 PD e2e SIMULATION:Mach-Zehnder EOM 1 → 33 MHz EOM 2 → 166 MHz EOM 3 → 29 MHz EOM2 EOM1 EOM3 Napoli, October 22, 2004

  19. MAIN BOXES of Mach-Zehnder package Mach-Zehnder optics Mach-Zehnder control extra noise filter feedback + actuator Napoli, October 22, 2004

  20. LOCK ACQUISITION of the MACH-ZEHNDER Simulation time 0.25 s Seismic Noise 0-0.05s open loop 0.05-0.1s gain=0.02 0.1-0.15s gain=1 0.15-0.2s gain=10 0.2-0.25s gain=100 Mirror displacement Error signal MZ Lock acquired Control signal Napoli, October 22, 2004

  21. Mach-Zehnder Feedback Filter TF (real and simulated) Boost: 1 Pole @ 100 Hz, 1 zero @ 1 kHz 1 Pole @ 220 Hz 3 Poles @ 300 kHz Dc Gain 80 dB Napoli, October 22, 2004

  22. Mach-Zehnder Open Loop TF (real and simulated) Napoli, October 22, 2004

  23. Mach-Zehnder Closed Loop TF (real and simulated) Napoli, October 22, 2004

  24. e2e SIMULATION: 4Om/AdvLIGO optical configuration IFO with Arms IFO Central part Napoli, October 22, 2004

  25. e2e SIMULATION:4Om/AdvLIGO package Mach-Zehnder No SBs on SBs optics laser signals monitoring EOMs in series SBs on SBs mirror positions Napoli, October 22, 2004

  26. e2e SIMULATION:4Om/advLIGO package Signals Monitoring Mirrors positions I signal Q signal Napoli, October 22, 2004

  27. [value (e2e) – value (Twiddle)] value (Twiddle) % = EQUILIBRIUM FIELDS VALUES COMPARISON between TWIDDLE and e2e RESULTS EOMs in series Good agreement between the two simulations TWIDDLE is a frequency domain simulation code using the Mathematica framework Napoli, October 22, 2004

  28. EQUILIBRIUM FIELDS VALUES e2e RESULTS EOMs in paralell (Mach-Zehnder) Modulation depth = 0.1 Napoli, October 22, 2004

  29. EQUILIBRIUM FIELDS VALUES e2e RESULTS EOMs in paralell (Mach-Zehnder) Modulation depth = 0.4 Napoli, October 22, 2004

  30. e2e SIMULATION: Summary • Mach-Zehnder: • Transfer functions and displacement noise simulation of the Mach-Zehnder package • Comparison with 40m raw data • good agreement between simulation and raw data but improvements are necessary to match them better • 40m/advLIGO: • Calculation of the equilibrium fields values • configuration with EOMs in series • to compare with Twiddle results and validate optics • configuration with Mach-Zehnder • just to evaluate the equilibrium fields values Napoli, October 22, 2004

  31. PLANNING Short term (next months): • e2e validation of the phase noise introduced by the mirror displacements • already calculated by S.Kawamura with Finesse • Length Sensing matrix implementation • To be added: suspensions, electronics, mode cleaner … more Long term (next year): • Improvement of the simulation speed: re-summation cavity formulation • → technique used to avoid full propagation in the ITF central part • Application of all acquired knowledges to Upgraded Virgo Napoli, October 22, 2004

  32. Considerations for Virgo What happens to Virgo sensitivity curve if the signal recycling mirror is added? First examples done by P.Hello using new parameters (M.Punturo Virgo note on) Advanced Virgo Sensitivity curve depends on SR reflectivity !! Application: • e2e framework • Siesta framework • something new … Time domain model for Virgo using Napoli, October 22, 2004

  33. Application to Virgo Thermal noises contributions to the sensitivity : Numbers extracted from Michele’s note : SHOT NOISE CONTRIBUTION to the SENSITIVITY : • Parameters used : • input LASER power = 100 W • Arm Finesse = 600 • recycling gain = 50 (= 1/litf) • SR variable parameters : • tuning frequency fsrc • SR mirror reflectivity where FSR is the SR transfer function Napoli, October 22, 2004

  34. Details of the SR transfer function : In fact the SR transfer function can be written as : (2 contributions of the 2 sidebands) (only one is relevant except when tuned at zero-frequency) where td and rd are the transmittivity ans reflectivity of the SR mirror F is the finesse of the SR cavity L is the SR cavity length nsr is the SR tuning frequency F is the reflectivity phase of the arm cavities : (very good approximation for undercoupled cavities) Where is the arm cavity cut-off frequency Napoli, October 22, 2004

  35. Sensitivity (/Hz1/2) Virgo AdvVirgo AdvVirgo with SR Frequency (Hz) SIGNAL RECYCLING for Virgo Example of SR sensitivity curve Arm finesse = 600 fsr = 800 Hz rsr = 0.9 Napoli, October 22, 2004

  36. Virgo AdvVirgo AdvVirgo with SR SIGNAL RECYCLING for Virgo Sensitivity (/Hz1/2) Arm finesse = 600 fsr = 800 Hz rsr = 0.8 Frequency (Hz) Napoli, October 22, 2004

  37. Virgo AdvVirgo AdvVirgo with SR SIGNAL RECYCLING for Virgo Sensitivity (/Hz1/2) Arm finesse = 600 fsr = 800 Hz rsr = 0.95 Frequency (Hz) Napoli, October 22, 2004

  38. Virgo AdvVirgo AdvVirgo with SR SIGNAL RECYCLING for Virgo Sensitivity (/Hz1/2) Arm finesse = 600 fsr = 800 Hz rsr = 0.99 Frequency (Hz) Napoli, October 22, 2004

  39. Some links: • http://www.ligo.caltech.edu • http://www.ligo.caltech.edu/~e2e • http://www.ligo.caltech.edu/ajw/40m_upgrade.html LIGO homepage e2e homepage 40m homepage Thanks for your attention !!!! Napoli, October 22, 2004

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