Hakan E. Tureci, H.G.L. Schwefel, A.D. Stone, N.B. Rex and R.K. Chang

It has been shown that micro-cavity lasers represent a realization of a wave-chaotic system which presents
many unsolved problems for optical physics. These systems can be classified as "refractive billiards",
where a phase space approach is particularly rewarding. In the past, various mode geometries have been
observed in such micro-lasers: whispering gallery modes, bow-tie modes and square-modes based on periodic
orbits which are either stable or marginally stable. Recently, on a GaN based micro-laser, a scarred mode
was found to lase, which is based on an unstable triangular periodic orbit. I will report our analysis of
this experiment, and some recent experiments based on polymer samples, which demonstrate further evidence
for the fertility of a phase-space approach.