WAVELENGTH SPACING TUNABLE MULTICHANNEL FILTER BASED ON SUPERIMPOSED CHIRPED FIBER BRAGG GRATINGS

摘要

A wavelength spacing tunable multichannel filter is provided to freely increase or decrease a channel width by symmetrically changing a chirp ratio of superimposed chirped fiber Bragg gratings. A wavelength spacing tunable multichannel filter includes a first chirped fiber Bragg grating and a second chirped fiber Bragg grating. The second chirped fiber Bragg grating is formed to be superimposed on the first chirped fiber Bragg grating with an offset length between them. The multichannel filter includes a sampling chirped fiber Bragg grating having multichannel properties. A chirp ratio of the multichannel filter is adjusted to be symmetrical in a horizontal direction by using one of a bending, temperature-adjusting, and straining processes.