Abstract

An effective method for efficient power extraction from planar waveguide or thin slab solid-state lasers is provided by the hybrid configuration, which combines an unstable lateral resonator with a stable or waveguide resonator in the transverse direction. A two-mirror configuration is preferred for ease of alignment and simplicity and previously we have used spherical optics [1], but transverse mode selection has relied on the use of an intra-cavity slit. More general 2-mirror resonators require at least one toroidal mirror surface, with large curvature (R_L ~ 0.2m to >1m) in the lateral direction and small curvature (R_T ~ 15 to 50mm) in the transverse direction. For a large core height planar waveguide as in [1], R_T and the mirror distance can be chosen to obtain mode selectivity by low-loss coupling of the fundamental mode into the core, combined with spread of higher order modes into the cladding. However, additional selectivity may be available if the transverse size of the toroidal mirror is restricted to form a slit-shaped mirror. Such mirrors are difficult to fabricate by conventional means.

© 2009 IEEE