Abstract

A buried heterostructure (BH) laser¹⁾ has many attractive features such as low threshold and stable fundamental transverse mode oscillation. Recently, we reported a new type of a channeled substrate buried heterostructure laser²⁾ called as a buried convex waveguide structure (BCS) laser³⁾. The BCS laser consistently succeeded in stable fundamental transverse mode oscillation, but the fundamental transverse mode oscillation was limited below 5-6 mW/facet. The suppresion of the higher order modes in the convex waveguide is due to the fact that thickness fluctuations of the tapered portion bring about large scattering loss for higher order modes⁴⁾. The large difference of the scattering loss between fundamental mode and higher order modes makes it possible to obtain stable fundamental mode lasing up to high power level. This may be realized in a truncated convex waveguide where the fundamental mode mainly distributes in the center flat region with small loss but the higher order modes distribute over the tapered portion giving large scattering loss. In this paper, we report an improved BCS laser with a truncated convex active region which enables to realize stable fundamental mode lasing up to 20 mW/facet, and its reproducible fabrication technique.

© 1982 Optical Society of America