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 Deltanall in the predetermined range is represented by the sum of index perturbations Deltank (k=1-K) of periods Lambdak according to the respective K wavelength bands. Furthermore, at least one set of phases out of phases phik (k=1-K) of the index perturbations Deltank 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.