| 摘要 |
Because height H and height h are sufficiently large as shown in FIG. 2 , a semiconductor layer formed above the convex part through crystal growth always has thickness smaller than a semiconductor layer formed at the central part of the cavity (concave part existing between two convex parts). That tends to occur until at least the active layer 106 is completed. As a result, a window structure, which has band gap energy sufficiently larger than the central portion of the cavity owing to its quantum size effect, can be obtained around the output facet of the cavity. Also, an n-type clad layer 104 is formed between the etching plane having etching damage and the semiconductor layer constructing a waveguide. That enables to relax or overcome negative effect which is caused by damage left on the etching plane toward crystallinity of the waveguide.
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