Patent ID: 6882777
Filing Date: 2005-04-19
Classification: G02B

Abstract:
1. 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 said diffraction grating selectively reflects light in a reflection band out of light guided through the optical waveguide, wherein, where a first band is defined as a wavelength band with a maximum bandwidth out of continuous wavelength bands for which the transmittance is not more than T the perturbation of refractive index of said diffraction grating is of antero-posterior symmetry with respect to the center on a center position of said predetermined range, T R a ratio (B a maximum group delay difference (in units of ps) caused by reflection of light in said first band by said diffraction grating is not more than 0.011×exp(7.86×B