| 摘要 |
PROBLEM TO BE SOLVED: To make the stopping band width of an optical waveguide grating narrow without making the grating length long. SOLUTION: The optical waveguide such an optical fiber 1 whose core 1a has a 0.35 to 1.5% mean specific refractive index difference is used and a radiation-mode coupling type grating (grating part 2) is formed to the fiber 1. The optical waveguide preferably has a single-mode type transmission characteristics in the operation wavelength range of the grating and in concrete, one of a 1.3μm zero-dispersion optical fiber, a cutoff shift optical fiber, and a dispersion shift optical fiber is preferably used. |
