Optical waveguide type grating element, production method thereof, multiplexer/demultiplexer module, and optical transmission system

摘要

The present invention relates to an optical waveguide type grating element and others in structure for decreasing absolute values of chromatic dispersion occurring in selective reflection of each of signal channels in a reflection band. The optical waveguide type grating element is provided with an optical waveguide in which signal light containing a plurality of signal channels spaced at a channel spacing lambda_i propagates, and a grating which is an index modulation formed over a predetermined range of the optical waveguide. Particularly, the optical waveguide type grating element has a transmittance of -20 dB or less for each of the signal channels in the reflection band, and has a reflectance of -20 dB or less for each of signal channels outside the reflection band. Furthermore, a deviation of a group delay time of each of the signal channels in the reflection band, which is caused by reflection in the grating, is 10 ps or less in a wavelength range of (lambda_CH-lambda_ix0.375/2) or more but (lambda_CH+lambda_ix0.375/2) or less, where lambda_CH is a center wavelength of each signal channel.