PROPERTIES OF THE TRANSVERSE EIGENMODE SET IN OPTICAL RESONATORS WITHAPERTURES

A method for numerical analysis of the eigenmode set of an optical res onator containing elements (e.g., apertures) with a nonnegligible diff raction effect is presented. With a simple example it is shown that th e presence of such elements may lead to quite complicated dependence o f modal losses, frequencies, and patterns on the cavity configuration. An increase in losses as the intracavity aperture decreases in size m ay be nonmonotonic, and modal frequencies may exhibit shifts up to sev eral percent of the free spectral range (the frequency interval betwee n consecutive longitudinal modes) and quick transitions or jumps acros s several tons of percent of the free spectral range. These properties of empty resonator modes might help to clarify the complexity of dyna mics occurring in some experimental devices such as self-mode-locked l asers.