| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently make the blocking rate of a radiation mode type optical waveguide grating large by forming the periodic change of waveguide structure in the direction of optical guide of the optical waveguide and providing a clad having the thickness thicker than the specified times of a core thickness. SOLUTION: A core 3 is formed in a clad layer 2 on a substrate 1 and the core 3 has a grating structure whose width is periodically changed in the direction (x) of an optical waveguide. Namely, the band-like trunk part 3a of the core 3 is extended in the direction (x) of the optical waveguide above the substrate 1 and a rectangular branch part 3b extended from the trunk part 3a in the direction of the width of the core 3 is formed along the direction (x) of the optical waveguide with a prescribed equal interval. This grating has a clad 2 with the thickness thicker than thirteen times of the thickness of the core 3. Consequently, re-coupling from a clad mode to a core transfer mode generated due to a thin lower clad layer is reduced and the blocking rate is increased. |
