Search

Abstract: A simple fiber-optic sensor based on Fabry–Perot interference for small displacement measurement is investigated both theoretically and experimentally. A broadband light source is coupled into a Fabry–Perot cavity formed by the surfaces of a sensing fiber end and the measured object. The interference signals from the cavity are reflected back into the same fiber. A small displacement via changes in cavity length can be obtained by measuring the wavenumber spacing of the interference fringes. The experimental data meet with the theoretical values very well. Given the light source bandwidth of 40nm and the initial distance of 30μm, the proposed displacement sensing system could achieve high resolution measurement of 16nm. [Copyright &y& Elsevier]

Abstract: A fiber Bragg grating (FBG) interrogating technique based on the relative intensity–demodulating and the demultiplexing of an arrayed waveguide grating (AWG) is presented in this paper. The analytical simulation and the experiment validate the feasibility of this setup. Both theoretical and experiment results show that the shift of the Bragg wavelength of the FBG sensors can be precisely interrogated by the relative intensity reading of two-adjacent-channels of the AWG-based demultiplexer. Errors caused by the light source fluctuation and micro-band losses can be reduced with the relative technique. This technique potentially offers a low-cost, compact, and high-performance solution for the interrogation of FBG distributed sensors. [Copyright &y& Elsevier]