LONG SEMICONDUCTOR LASER CAVITY IN A COMPACT CHIP

摘要

Long semiconductor laser cavities are placed in relative short length chips through the use of total internal reflection (TIR) surfaces formed through etched facets. In one embodiment, a laser cavity is formed along the perimeter edges of a rectangular semiconductor chip by using three 45 angled TIR facets to connect four legs of a ridge or buried heterostructure (BH) waveguide that defines the laser cavity. In other embodiments, even more TIR facets and waveguide legs or sections are employed to make even longer laser cavities in the shape of rectangular or quadrilateral spirals. These structures are limited in the spacing of adjacent waveguide sections, which if too small, can cause undesirable coupling between the sections. However, use of notches etched between the adjacent sections have been shown to decrease this coupling effect.