Mode control of heterojunction injection lasers and method of fabrication

摘要

Mode control both for longitudinal and fundamental transverse modes can be achieved by employing a mesa structure on the laser substrate during fabrication. The mesa will provide significant variations in the thickness of one or more hetrostructure waveguiding layers that may be fabricated on the mesa formed substrate. As a result, the equivalent index of refraction for each waveguiding layer will be different. For longitudinal mode operation, a branching directional coupler can be directly fabricated during preferential LPE growth due to the presence of the mesa formed on the substrate. For fundamental transverse mode operation, oscillation can be restricted to a high gain region in a waveguiding layer due to the presence of the mesa and thickness variation and curvature in the active layer. Connected or juxtaposed stripe contact geometry can also be employed to provide a multicavity effect in a light waveguiding layer to enhance longitudinal mode selectivity.