We present a closed-loop technique for measuring wavelength shifts associated with fiber Bragg gratings by using a fused biconical wavelength division multiplexer (WDM). The spectral response of the WDM is actively tuned by stretching of the coupling region to maintain a fixed coupling ratio at the reflected Bragg wavelength. The closed-loop operation allows sensitivities usually associated with a highly selective WDM to be obtained without compromising the measurement range. A simple theoretical model is presented together with experimental results for temperature and strain measurements.
© 1998 Optical Society of America
(060.1810) Fiber optics and optical communications : Buffers, couplers, routers, switches, and multiplexers
(060.2340) Fiber optics and optical communications : Fiber optics components
(060.2370) Fiber optics and optical communications : Fiber optics sensors
Francisco M. Araújo, Luís A. Ferreira, José L. Santos, and Faramarz Farahi, "Demodulation Scheme for Fiber Bragg Grating Sensors Based on Active Control of the Spectral Response of a Wavelength Division Multiplexer," Appl. Opt. 37, 7940-7946 (1998)