| 摘要 |
A semiconductor diffraction grating device includes a semiconductor substrate having a principal surface, a semiconductor core layer and a semiconductor cladding layer provided on the principal surface, and a chirped grating structure provided between the semiconductor core layer and the semiconductor cladding layer. The chirped grating structure includes a first region, a second region, and a third region arranged in that order in a predetermined axis direction, the first, second, and third regions including a plurality of projections constituting a chirped grating. The plurality of projections are provided at placement positions arranged with a predetermined pitch in the predetermined axis direction. The coupling coefficient &kgr; of the chirped grating monotonically increases in the predetermined axis direction to a predetermined value in the first region, remains flat in the second region, and monotonically decreases in the predetermined axis direction from the predetermined value in the third region.
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