Refractive index control optical semiconductor device

摘要

A refractive index control optical semiconductor device includes a semiconductor p-n junction structure, and a refractive index control semiconductor layer. The semiconductor p-n junction structure outputs light with a forward current. The refractive index control semiconductor layer is formed on a semiconductor substrate, is stacked on the semiconductor p-n junction structure to constitute an optical waveguide, causes a refractive index change of light to occur by carrier injection, and includes a multi-quantum well structure formed by alternately stacking a semiconductor quantum well layer and a barrier layer having a bandgap larger than that of the semiconductor quantum well layer at a plurality of periods. The semiconductor quantum well layer has a lattice constant smaller than that of the semiconductor substrate. The thickness of the semiconductor quantum well layer is set such that a lowest heavy hole sub-band and a lowest light hole sub-band of the semiconductor quantum well layer have nearly the same energy at a GAMMA -point in a wave number space.