| 摘要 |
PURPOSE: To facilitate manufacture and to easily provide desired transmission characteristics by providing a specified Bragg grating formed in an optical waveguide medium in an optical filter. CONSTITUTION: A 1-to-4 coupler 4 distributes multiplex signals respectively into branches 6 provided with band-pass filters 8 corresponding to one of demultiplexed signal channels. The respective band-pass filters 8 are provided with at least one Bragg grating formed in the optical waveguide medium 2 of the corresponding branch 6. Then, such respective Bragg gratings representatively satisfy Bragg conditions and indicate one reflection spectrum peak corresponding to the wavelength of light reflected in a reverse direction so as to practically guide reflected emission light in the optical waveguide medium. The spectrum area of low transmissivity is stipulated by such Bragg's peak. Then, the respective Bragg's peaks contribute to at least some of the blocking bands of the band-pass filters 8. |
