I have revived my old finesse model of the four filter cavities to try to model the transfer function of power through the cavities.

cavity_modes.pdf (and the .png version) shows a single cavity with a laser going into it at 1550 nm while being phase modulated at 15.6 MHz. the cavity length is offset by 15.6 MHz. each peak is calculated individually and then combined where each peak represents an n,m mode. Since the Gouy phase of the cavity is about 120 degrees, only the third modes should get through. The heights of the modes have been given a per mode attenuation of  (1 / (m + n + 1)**2) and 0.001 times that for every non third mode. These values are arbitrary and will be updated in the future. This single cavity goes up to 5 TEM modes.

Work on this modeling is ongoing.