Cross-talk and noise issues in coherence multiplexed in-line Fabry-Perot etalon (ILFE) strain sensor

In this paper we have investigated the cross-talk and noise issues that arise in serial multiplexing of In-Line Fiber Etalon (ILFE) strain sensors using three different topologies. First, the broadband source is numerically modeled to preserve all the artifacts in the line structure. Second, the effect of beam expansion in the non-guiding ILFE cavity is investigated. The two models are combined to calculate the fringe contrast, signal and background power, the shot-noise and cross-talk noise in the system. Also the signal extinction is studied as a function of mismatch between the ILFE gagelength and path-matching interferometer gagelength. Finally, suggestions are made to enhance the fringe contrast in ILFE based systems.