We propose and experimentally demonstrate a novel switchable and discretely tunable comb filter based on a thermally induced linearly chirped fiber Bragg grating. Experimentally we achieved a thermally induced optical bandpass filter that has eight switchable passband peaks with peak separations of 1.6 and 3.2 nm, a very narrow bandwidth (as small as 10 pm) of each peak, a tunable range of 16.5 nm, and a greater than 25 dB rejection ratio. Two spectral peaks separated by only 0.8 nm were also obtained with this comb filter. This filter provides the unique advantages of an all-fiber structure, switchable spectral peaks, independent tuning of the center wavelength and wavelength spacing of the spectral peaks, low polarization sensitivity, simple structure, ease of fabrication, and low cost.
© 2005 Optical Society of America
(050.5080) Diffraction and gratings : Phase shift
(060.2340) Fiber optics and optical communications : Fiber optics components
(230.1150) Optical devices : All-optical devices
(350.2460) Other areas of optics : Filters, interference
Fiber Optics and Optical Communications
N. Q. Ngo, D. Liu, S. C. Tjin, Xinyong Dong, and P. Shum, "Thermally switchable and discretely tunable comb filter with a linearly chirped fiber Bragg grating," Opt. Lett. 30, 2994-2996 (2005)