A theoretical model is developed to address the fringe visibility and additional phase in the interference spectra of low-finesse extrinsic optical fiber excited Fabry-Pérot interferometers. The model described in the paper applies to both single-mode and multimode fiber excitations; according to the theory, the fringe visibility and additional phase term are primarily determined by the working wavelength and angular power density distribution outputting from the excitation fiber, rather than

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... iber, rather than based on spatial and temporal degree of coherence. Under certain approximations, the output interference intensity and the spatial power density distribution projected onto the fiber axis form a Fourier-transform pair, which potentially provides a tool for spatial density distribution analysis of fiber output. With excellent agreement with experiments, the theory presented in this paper leads to design guidelines for Fabry-Pérot interferometric sensors and insightful physical understanding of such devices. Exact analysis of low-finesse multimode fiber extrinsic Fabry-Perot interferometers," Appl. Opt. 43(24), 4659-4666 (2004). 16. M. Han and A. Wang, "Mode power distribution effect in white-light multimode fiber extrinsic Fabry-Perot interferometric sensor systems," Opt.