Tunable and switchable optical bandpass filters using a single linearly chirped fiber Bragg grating

We propose a new method for the development of tunable optical bandpass filters (TOBFs) by thermal tuning of a single linearly chirped fiber Bragg grating (LCFBG). Two resistance wires are placed across the grating section as thermal heads to introduce local temperature changes into the LCFBG. A passband peak is thus generated within the stopband of the LCFBG due to the local Bragg wavelength shift and thermally induced temporary phase shifts. The passband peak can be tuned by scanning the resistance wires along the LCFBG. The developed TOBF has a bandwidth of similar to0.2 nm, an out-of-band rejection range of similar to20 nm, a continuously tuning range of similar to15 nm, a minimum insertion loss of similar to4 dB, and a maximum rejection ratio of similar to25 dB. (C) 2004 Elsevier B.V. All rights reserved.