OPTICAL WAVEGUIDE DIFFRACTION GRATING DEVICE, METHOD FOR FABRICATING OPTICAL WAVEGUIDE DIFFRACTION GRATING DEVICE, MULTIPLEXING/DEMULTIPLEXING MODULE, AND OPTICAL TRANSMISSION SYSTEM

摘要

A diffraction grating device according to the present invention is a diffraction grating device in which a diffraction grating based on perturbation of refractive index is formed through a predetermined range in a light guide direction in an optical waveguide and in which the diffraction grating selectively reflects light in a reflection band out of light guided through the optical waveguide. In the diffraction grating device, the reflection band is divided into K (K ≥ 2) wavelength bands, and the perturbation of refractive index Δnall in the predetermined range is represented by the sum of index perturbations Δnk (k = 1-K) of periods Λk according to the respective K wavelength bands. Furthermore, at least one set of phases out of phases ϕk (k = 1-K) of the index perturbations Δnk at a center position of the predetermined range are different from each other. This permits provision of the diffraction grating device in a short total length, at low cost, and with excellent reflection and transmission characteristics.