SEMICONDUCTOR OPTICAL APPARATUS

摘要

The invention relates to a semiconductor optical apparatus (100), wherein the semiconductor optical apparatus (100) comprises a first waveguide region (101) defining a first mode size and a second active waveguide region defining a second mode size being smaller than the first mode size. The second active waveguide region is optically coupled to the first waveguide region (101) and the second active waveguide region comprises a lower multiple quantum well layer (103) and an upper multiple quantum well layer (105) located above the lower multiple quantum well layer (103). The lower multiple quantum well layer (103) is physically separated from the upper multiple quantum well layer (105) by a spacer layer (107). The upper multiple quantum well layer (105) comprises a mode transformation region (105a) configured to reduce the size of an optical mode from the first mode size to the second mode size. In an implementation form, the first waveguide region (101) is a first waveguide active region comprising a further multiple quantum well layer and the modal index defined by the further multiple quantum well layer is substantially equal to the modal index defined by the lower multiple quantum well layer (103).