EFFECTIVE-INDEX DESIGN OF A SHAPED CONTINUOUS UNSTABLE RESONATOR FOR HIGH-POWER LASER-DIODES

A geometric approach for a new type of unstable resonator, for high po wer and coherent semiconductor lasers, is described. The design is bas ed on a theoretical model which predicts single mode operation for a w ide waveguide with negative parabolic lateral effective refractive ind ex (ERI) variation. A physical two waveguide model (or waveguide compo sed o two parts) is used to explain the functioning of such cavity. Ra diation taking place in a primary high index region is directed by a s econdary one where the optical intensity is lower. Analysis using the GRIN code shows only low order modes survive after multiple reflection s.