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requirements

requirements. AdvLIGO – optical layout. AdvLIGO PSL – subsystem layout. power stabilizaiton. pre-. long. 170W. power. mode. front end. mode. baseline. stages. cleaner. 20W. 200W. cleaner. cavities. reference. cavity. frequency stabilization. Power / Beamprofile:

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requirements

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  1. requirements

  2. AdvLIGO – optical layout

  3. AdvLIGO PSL – subsystem layout power stabilizaiton pre- long 170W power mode front end mode baseline stages cleaner 20W 200W cleaner cavities reference cavity frequency stabilization

  4. Power / Beamprofile: 165W in gausian TEM00 mode less than 5W in non- TEM00 modes Drift: 1% power drift over 24hr. 2% pointing drift Control: tidal frequency acuator +/- 50 MHz, time constant < 30min power actuator 10kHz BW, +/-1% range frequency actuatot BW:<20o lag at 100kHz, range: DC-1Hz: 1MHz, 1Hz-100kHz: 10kHz Advanced LIGO PSL – requirements

  5. frequency noise requirement

  6. intensity noise requirement

  7. further PSL requirements • interfaces to detector control software • interfaces to DAQ system • environmental requirements: size, power, cooling • reliability to meet detector duty cycle goal • easy to maintain (change of items with lifetimes < 2years)

  8. concept

  9. high power ring laser 200W GEO typring laser15W spatial filterresonator (PMC) NPRO1W frequencyreferenceresonator AOM PSL optical layout

  10. NPRO output QR f f EOM FI BP FI modemaching YAG / Nd:YAG 3x2x6 optics QR f f BP YAG / Nd:YAG / YAG HR@1064 f 2f f 3x 7x40x7 HT@808 20 W Master High Power Slave Advanced LIGO Laser Design

  11. PSL – stabilization scheme intensity stabilizationouter loop injection locking intensity stabilizationinner loop PMC loop frequency stabilizationinner loop frequency stabilizationouter loop

  12. pre-stabilized -LIGO 10W laser length controll intensity controller pre-mode cleaner EO power NPRO amplifier to suspended mode cleaner temp PZT EO phase shifter reference cavity AO frequency contoller mixer

  13. LIGOI reference cavity, AOM, tidal correction

  14. pre-modecleaner 713 MHz free spectral range linewidth: 162 kHz in s-pol. , 3.2 MHz in p-pol. circulating power 0.135MW/cm2 (for p-pol.), 2.64MW/cm2 (for s-pol.) linewidth required to filter RIN(@25MHz) of 180W laser: 3.7MHz

  15. status

  16. high power ring laser 200W GEO typring laser15W spatial filterresonator (PMC) NPRO1W frequencyreferenceresonator AOM PSL set-up

  17. Nd:YAG Master-Laser NPRO (non-planar ring oscillator) by Innolight* • output power: 800mW • frequency noise: [ 10kHz/f ] Hz/sqrt(Hz) • power noise: 10-6 /sqrt(Hz) * US dristibution: Resonant optics Corp., San Martin CA

  18. High Power Locking SchemeMaster • 2W Miser Mephisto 2000 Innolight • EOM: New Focus @ 29,02 MHz • Isolator: Gsänger

  19. GEO 600 Slave Laser

  20. performance of the LIGOI frequency stab

  21. High Power Locking SchemeMedium Stage • 12 W med. power stage based on GEO 600 laser design opt ~ 30 % • Isolator: Gsänger high power design

  22. GEO 600 Slave Laser Prototype IIFrequency Stability

  23. 12W injection-locked laser-system NPRO (non-planar ring oscillator) master laser, output power: 800mW slave laser optical components mounted on rigid resonator-spacer (Invar) 12W output power (< 5% in higher TEM modes) injection-locking stable over days

  24. High Power Slave 87 W output power linear polarized single transverse mode M2x,y ~ 1,2

  25. Experimental/Diode Temperature Control laser diode JENOPTIK 30 W, fiber coupled, NA 0.22; 800 m temperature resolution: 0.01K temperature fluctuations: 2-3 digits temperature stability better than 0.05K

  26. 4 boxes • each 10 X 30 W fiber-coupled diodes  1200 W pump Power Experimental/Diode Box user interface 4 systems (boxes) 40 temperatures laser diode (10) heat sink (2) 4 current controls (1 per box) ADC/DAC upcoming: • 40 diode power measurements  laser power control for each diode overtemp interlocks peltier drivers

  27. High Power Locking Scheme • 87 W high power slave single transverse mode M2 ~ 1,2 opt ~ 23 %

  28. High Power Locking Scheme

  29. Results First high power injection locked laser system 87 W linear polarized, single frequency, single transverse mode ( total power of all systems ~ 101 W ) total optical efficiency 22% locking direct to 2 W master possible single frequency output power ~ 70 W

  30. Beam Characterization Beat signals of free running slave  no higher order modes detect Beam profile of locked system  M2~1.1 , less elliptical beam

  31. Relock Time relock time < 500 ms faster relock possible depending on piezo ramp

  32. System Optimization To get full injection locked power following things has to be optimized: • Modemaching in the high power slave ( FI with compensated thermal lens ) • Outputcoupler of high power slave • optimize gain overlap of different Lasers • implement pumplight optimization

  33. next steps

  34. Pump Concepts mode selective pumping w = 1mm

  35. Pump Light Homogenization  30 % more output power with homogenization  better gain overlap and less distortion for low order modes

  36. New Head Design

  37. 2.5 cm Pump Chamber water flow

  38. Birefringence compensation Find working point with less birefringence

  39. Pump Light Homogenization fluorescence w/o homogenization

  40. Homogenization of Pump Light simulation 10 x 800 µm measured 30 x 800 µm

  41. Pump Concepts mode selective pumping w = 2 mm

  42. Optimization of Pump Light Distribution alignment of homogenous and centered pump light profile pump power calibration for PD-readout

  43. Optimize Resonator • Test different laser rods 4,5 mm • Test different pump spot sizes  find best laser design before doubling the system

  44. Advanced Ligo Laser 1st. Step • Optimized laser head with respect to beam quality and output power • up to now 100 W of output power in single transverse mode are demonstrated

  45. output QR f f BP from Master QR f f HR@1064 f 2f f HT@808 Advanced Ligo Laser 2st. Step

  46. pump light distribution • ray tracing • analytical approximation • experimental data Finite Element Method for calculating • temperature distribution • mechanical stress • deformation heat generation gain cooling wave propagation through inhomogenous medium • finite differencing • split step fourier approach calculation of optical properties • thermal lens • stress-induced birefringence k-vector Modeling/Overview

  47. Model assumption: cylinder symmetrical pump light distribution model takes into account temperature dependent properties wavelength dependent absorption coefficient temperature dependent heat conducitvity temperature dependent expansion coefficient temperature dependent dn/dT

  48. initial distributed E(x,y,z0) (e. g. noise) medium free propagation mirror/aperture free propagation medium free Propagation output power beam quality mirror/aperture free Propagation no yes convergence ? Fox/Li Approach Iterative Solution of Kirchhoff integral equations • inhomogenous distributed gain, refractive index, birefringence concentrated in gain/phase sheets • propagation between gain/phase sheets and in free space described by FFT propagator

  49. <10 nm Abberations/End Pumped vs. Transversally Pumped

  50. Thermal Modeling/Temperature Distribution varying with pump spot diameter (pump power kept constant) 500 m

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