Here are two plots showing the ideal behavior of some DC signals and REFL9 signal during reduction of the CARM offset. They are computed by optickle with the designed optical parameters except for the modulation depths which are now 0.17 rad and 0.3 rad for 9 and 45 MHz modulations respectively.

Attachment 1:

A plot of some DC signals as a function of the CARM offset. TRX (show in red) is normalized by the single arm power. It reaches 1350 with zero CARM offset, indicating that the recycling gain is about 41. REFL_DC (shown in cyan) is normalized such that it is unity when the CARM has a large offset. The same normalization is applied to POP_DC (shown in brown) as well. The black curve is derived simply by sqrt(normalized TRX + normalized TRY).

Attachment 2:

A plot of REFL_DC, AS_DC and REFL9 demodulated signals as a function of the CARM offset. AS_DC is in mW while REFL_DC is in Watts. The demod signals are in an arbitrary unit.