Parameter	Value	Virgo value	Difference
Power recycling cavity length	11.953 m	12.053 m	-0.100 m
Input mode cleaner length	143.434 m	143.573 m	-0.139 m
Schnupp asymmetry	0.04 m	0.878 m	-0.838 m
Signal recycling cavity length	11.947 m	11.980 m	-0.033 m
Distance BS-IMX	5.993 m	6.512 m	-0.519 m
Distance BS-IMY	5.953 m	5.634 m	+0.319 m
Distance BS-PRM	5.980 m	5.980 m	+0.000 m
Distance BS-SRM	5.974 m	6.000 m	-0.026 m
SB1 modulation frequency	6270339.2 Hz
SB2 modulation frequency	87784748.7 Hz
SB3 modulation frequency	8360585.6 Hz

Finesse simulation

The Finesse input file: advirgo_lmod_ss_12m.kat

Input power (before power recycling mirror) is 100 W.

The correct resonance conditions of all sidbands have been checked. Here are the results.

Arm cavity resonance

The signal and power recycling mirror have been removed and the north cavity length changed over one free spectral range. Here is the transmitted power:

Power recycling cavity resonance

The arms are kept on resonance for the carrier, the signal recycling mirror is removed and the power recycling cavity length swept over one free spectral range. The beam splitter pick-off power is shown here:

Transmission to anti-simmetric port

The signal recycling mirror is remove, the power recycling cavity and the arm cavities are kept on resonance, MICH is swept over one free spectral range. The anti-symmetric port power is shown here:

Signal recycling cavity resonances

Arms and power recycling cavities are on resonance, MICH is tuned to dark fringe, the signal recycling cavity length is changed over one free spectral range around the RSE value of 0 degrees:










































As expected at the operating point:

• SB1 is close to anti-resonant in the arms, resonant in the PRC, has small transmission to ASY and it is anti-resonant in SRC
• SB2 is enough detuned from cavity resonance, is anti-resonant in the PRC, has significant transmission to ASY and it is resonant in SRC.
• SB3 is not resonant in arms, not resonant in PRC, has small transmission to ASY and it is not resonant in SRC