Narrowband transmission filter using Bragg grating in series and wavelength division demultiplexer using the filter

摘要

1. The technical field to which the invention described in the claims belongs;The present invention relates to a narrowband transmission filter and a wavelength division demultiplexer using the filter.;2. Technical challenges to be solved by the invention;The present invention relates to a narrow-band transmission filter for converting an operating wavelength using a wavelength-variable toilet connected to a Bragg diffraction grating slightly different in center wavelength and capable of converting the center wavelength of each Bragg diffraction grating, To provide a multiplexer.;3. The point of the solution of the invention;In the present invention, when two grating diffraction gratings whose center wavelengths are slightly different from each other with a slightly different grating period and effective refractive index are connected in series, the transmission band and the long wavelength of the long wavelength side of the Bragg diffraction grating The transmission band is formed at the overlapping portion of the transmission band of the short wavelength side of the Bragg diffraction grating and the difference of the center wavelength of the two Bragg diffraction gratings is appropriately adjusted to be slightly larger than the sum of half the bandwidth of each Bragg diffraction grating The wavelength of the transmission band can be narrowed and the wavelength of the reflected wave can be changed by varying the reflected central wavelength using a wavelength variable toilet which can convert the grating period and the effective refractive index of each Bragg diffraction grating , A narrowband transmission filter is connected in series or parallel for use on the receiving side of the WDM system The signal of the desired wavelength can be separated.;4. Important Uses of the Invention;The present invention is used on the receive side of a wavelength division multiplexed (WDM) system.