LIGO- G R Telecon on June, Mach-Zender interferometer to eliminate sidebands of sidebands for Advanced LIGO Osamu Miyakawa, Caltech LIGO- G R
Telecon on June, Signal extraction of AdvLIGO Two sidebands are used to separate arm cavity signals and Central part (Michelson, PR, SR) signals. Arm cavity signals are extracted from beat between carrier and f 1 or f 2. Central part (Michelson, PR, SR) signals are extracted from beat between f 1 and f 2, not including arm cavity information. f1f1 -f 1 f2f2 -f 2 Carrier(Resonant on arms) Single demodulation Arms information L + and L Double/differential demodulation Central part information l +, l and l s
LIGO- G R Telecon on June, Sidebands of sidebands Sidebands of sidebands are produced by two series EOMs. Beats between carrier and f 2 +/ f 1 disturb central part. Sidebands of sidebands are amplitude modulation. Simulation Real world f1f1 -f 1 f2f2 -f 2 Carrier f1f1 -f 1 f2f2 -f 2 Carrier
LIGO- G R Telecon on June, l + signal with sideband of sideband No offset Big disturbance by carrier Some small disturbance Carrier resonance No offset
LIGO- G R Telecon on June, Signal matrix Original signal matrix Signal matrix with sideband of sideband
LIGO- G R Telecon on June, What should we do? Continue this optical setting with sidebands of sidebands? Change experimental setup to kill sidebands of sidebands?
LIGO- G R Telecon on June, Mach Zehnder interferometer »1/2 modulation index (1/4 sideband power) »Need one more control »Amplitude noise, frequency noise Michelson interferometer »Same modulation index as series EOMs »Faraday-isolator »Need one more control »Amplitude noise, frequency noise 2 more AOM to kill 133MHz and 199MHz »1/2 carrier power »Need to adjust phase and amplitude Using a broad band EOM to kill 133MHz and 199MHz »Not easy to kill amplitude modulation To eliminate sidebands of sidebands PD FI EOM
LIGO- G R Telecon on June, Control »Using internal modulation with 33MHz Mach-Zehnder on 40m PSL
LIGO- G R Telecon on June, Other issue Amplitude noise »Band width=100Hz »Not a problem. Mode matching »Will be a loss at MC, not a problem. Frequency noise »By Doppler shift or beam jitter, not a big issue. Carrier phase fluctuation caused by shake of EOMs »Will be shown on demodulation phase, probably OK.
LIGO- G R Telecon on June, Mach-Zehnder on 40m PSL PZT mirror BS1 BS2 PMC 33MHz EOM 166MHz EOM 29MHz EOM To PD