Patent ID: 6381069
Filing Date: 2002-04-30
Classification: G02B

Abstract:
A Bragg grating optical filter device having a group delay that is flat in the working band of width &Dgr;&lgr; around a center wavelength &lgr;C, said device having an input light guide, an output light guide, at least one optical circulator, and two fiber Bragg grating filters on light guides of center wavelength around the same center wavelength &lgr;C, and of reflection band width &Dgr;&lgr;B&gE;&Dgr;&lgr;; said Bragg gratings having almost periodic variations &Dgr;n1 in refractive index along the propagation axis of said light guide, said gratings having chirp, said chirp being a monotonic variation in the pitch of the index variation &Dgr;n1 along the axis, the two Bragg gratings having inverted chirp characteristics, wherein said chirp characteristics are approximately linear as a function of position along the propagation axis within each grating, and &Dgr;&lgr;BËœ&Dgr;&lgr;.