Spectrum analysis in cross-talk of series Fabry-Perot sensors in path-matching differential interferometry

The signals between cascaded Fabry-Perot sensors have serious cross-talk pr oblems due to complex phase interactions between sensors. However, cross-ta lks in cascaded Fabry-Perot sensors for demodulation in a path-matching dif ferential interferometry (PMDI) can be limited by corresponding path-matchi ng read-out systems. This paper presents a method of using spectrum analysi s to design the series Fabry-Perot sensors without cross-talk. The spectrum transfer function in a light source and Fabry-Perot cavities are simulated by a Gaussian distribution spectrum and a low-finesse reflectivity, respec tively. It shows that two series Fabry-Perot sensors without cross-talk can be designed precisely and following the same procedure, even more series F abry-Perot sensors without cross-talks in PMDI can be achieved. In-line fib er etalon (ILFE) as a Fabry-Perot cavity is used for multiplexing in the ex periment. Experimental data shows that the cross-talk between two series Fa bry-Perot sensors is limited. This design in two series Fabry-Perot sensors in PMDI can be applied to a two-parameter optical fiber sensors. (C) 1999 Elsevier Science Ltd. All rights reserved.