A novel dual-wavelength fiber Bragg grating and its application in dual-channel add-drop multiplexer

We report a new method for writing the dual-wavelength Bragg fiber gratings. The method is based on the photosensitivity of Ge-doped optical fibers. Our double-exposure technique enables a good control over the grating's reflectivity and the separation of the two Bragg wavelengths. A grating with two equal transmission peak of 20.5dB is obtained by using this method and the separation of the two Bragg wavelengths is about 0.8 nm. With the grating, an optical add-drop multiplexer (OADM) that allows dropping two fixed wavelength channels is proposed.