A general method of analyzing Michelson-based, multiple-mirror optical syst
ems, such as interferometers designed as gravitational-wave detectors, is d
escribed. Assuming that phase-modulated light is injected, signals that wil
l be generated by demodulation of the photocurrent anywhere in the system,
together with their frequency dependences, can be evaluated. Since this met
hod is based on the manipulation of matrices, it is appropriate for compute
rization. (C) 1999 Optical Society of America [S0740-3232(99)00507-4].