Influence of the Bending of the Outer Mirror in the External Fiber Fabry-Perot Interferometer on the Interference Signal Parameters

The basics of a simple analytical model of the EFPI interference signal, taking into account the bending of the outer mirror of the interferometer, are developed. The consideration uses a Gaussian beam model and a paraxial approximation using a ray transfer matrix. Simple approximate expressions for the Gaussian beam parameters are obtained taking into account the small ratio of the cavity length L and the curvature radius of the mirror RM. Calculations have shown that the influence of bending can be significant with sufficiently large, but practically possible L/RM ratios.