perugia, italy 20.09.05 reducing the noise in geo600 joshua smith for the geo 600 team
TRANSCRIPT
Perugia, Italy 20.09.05
Reducing the Noise in GEO600Reducing the Noise in GEO600
Joshua Smith for the GEO 600 team
Joshua Smith, Perugia, Italy
20.09.05
Noise Projections: hPNoise Projections: hP
Joshua Smith, Perugia, Italy
20.09.05
Noise Projections: hQNoise Projections: hQ
Joshua Smith, Perugia, Italy
20.09.05
Non-stationary NoiseNon-stationary Noise
At best the noise is very close to the Projections
Joshua Smith, Perugia, Italy
20.09.05
Shot + Dark NoiseShot + Dark Noise
Joshua Smith, Perugia, Italy
20.09.05
MI Detection Noises: PMI Detection Noises: P
Joshua Smith, Perugia, Italy
20.09.05
MI Detection Noises: QMI Detection Noises: Q
Joshua Smith, Perugia, Italy
20.09.05
Optimal h(t) Optimal h(t) Shot Noise Shot NoiseCombination optimized for SNR of h given:
hP = h + nP hQ = h + nQ
Joshua Smith, Perugia, Italy
20.09.05
Shot Noise: Next stepsShot Noise: Next steps Shot model: 5W to MPR, 7kW @ BS Currently have: 2W to MPR, 1.5-2kW @ BS Expect to be: sqrt(7/1.5) to sqrt(7/2) = 2.2 to 1.9 above design (just from cavity power)
Are currently about factor 4 from design levelo 10s of % from optimizations, reduction of dark noiseo rest (perhaps sqrt(2)) not yet understood
Next Week: Replace Laser Increase input laser power from 5W to 10W This will give sqrt(2), for the rest perhaps:
o Search for losses in power-recycling cavityo Reduce loss in modecleaners?
Joshua Smith, Perugia, Italy
20.09.05
Signal Recycling LongitudinalSignal Recycling Longitudinal
More aggressive filtering to reach design below 100Hz
Joshua Smith, Perugia, Italy
20.09.05
Laser Power NoiseLaser Power Noise
• Investigate quality of current signal after second modecleaner
• Use Input Port as error-signal for power stabilization 2nd/3rd loop
Joshua Smith, Perugia, Italy
20.09.05
MI Fast Auto-alignmentMI Fast Auto-alignment
• Implemented digital fast auto-alignment this week!
• Will allow aggressive filtering like that used in the SR loop
Joshua Smith, Perugia, Italy
20.09.05
Oscillator Phase NoiseOscillator Phase Noise
-Wenzel specs = -165dBc @ 1kHz
-Unable to measure better than 15dB above OPN in current setup
- Better RF setup aims to be limited by phase noise from oscillator
- Possible reduction of coupling coefficient with increased MI loop gain
Joshua Smith, Perugia, Italy
20.09.05
Michelson Diff. LongitudinalMichelson Diff. Longitudinal
-Required factor for fast path by whitening, bias reduction?
-Intermediate Mass FB not front-end limited, improve servo, possibly digital steeper low-passing above ~40Hz ?
Joshua Smith, Perugia, Italy
20.09.05
Nonlinear Actuator: Up-conNonlinear Actuator: Up-con
Joshua Smith, Perugia, Italy
20.09.05
Nonlinear Actuator: BeatsNonlinear Actuator: Beats
Joshua Smith, Perugia, Italy
20.09.05
Nonlinear Noise vs. Bias 600VNonlinear Noise vs. Bias 600V
Joshua Smith, Perugia, Italy
20.09.05
Nonlinear Noise vs. Bias 60VNonlinear Noise vs. Bias 60V
Joshua Smith, Perugia, Italy
20.09.05
Nonlinear Noise vs Bias VNonlinear Noise vs Bias V
Further decrease in bias not optimal !
Joshua Smith, Perugia, Italy
20.09.05
Summary Summary
Shot Noise (4x above design) sqrt(2) from power increase, 10-20% from modulation depth, etc. o Something else needed. Decrease finesse of MCs?
Oscillator Phase Noise Improved RF distribution to ensure –165dBc @ 1kHz limit from oscillatoro More MI gain
Michelson More whitening, noise mitigation slow path Signal Recycling Increased digital filtering Laser Power Use MIC VIS in-loop Auto-alignment Digital servo allows more aggressive
noise filtering
Shot Noise (4x above design) sqrt(2) from power increase, 10-20% from modulation depth, etc. o Something else needed. Decrease finesse of MCs?
Oscillator Phase Noise Improved RF distribution to ensure –165dBc @ 1kHz limit from oscillatoro More MI gain
Michelson More whitening, noise mitigation slow path Signal Recycling Increased digital filtering Laser Power Use MIC VIS in-loop Auto-alignment Digital servo allows more aggressive
noise filtering
Joshua Smith, Perugia, Italy
20.09.05
Optical LayoutOptical Layout