Goos-Haenchen shift and localization of optical modes in deformed microcavities

Recently, an interesting phenomenon of spatial localization of optical modes along periodic ray trajectories near avoided resonance crossings has been observed [J. Wiersig, Phys. Rev. Lett. 97, 253901 (2006)]. For the case of a microdisk cavity with elliptical cross section we use the Husimi function to analyse this localization in phase space. Moreover, we present a semiclassical explanation of this phenomenon in terms of the Goos-Haenchen shift which works very well even deep in the wave regime. This semiclassical correction to the ray dynamics modifies the phase space structure such that modes can localize either on stable islands or along unstable periodic ray trajectories.