Small-angle scattering due to mirror surface roughness is shown to couple the optical modes and deform the transmission spectra in a frequency-degenerate optical cavity. A simple model based on a random scattering matrix clearly visualizes the mixing and avoided crossings between multiple transverse modes. These effects are visible only in the frequency-domain spectra; cavity ringdown experiments are unaffected by changes in the spatial coherence, as they probe just the intracavity photon lifetime.
© 2005 Optical Society of America
Thijs Klaassen, Johan de Jong, Martin van Exter, and J. P. Woerdman, "Transverse mode coupling in an optical resonator," Opt. Lett. 30, 1959-1961 (2005)