Three-dimensional simulation of diffraction and absorption losses in all-fiber multilayer filters

Abstract

A rigorous modal three-dimensional calculation method is used to analyze the diffraction and absorption losses in Fabry-Perot (FP) multilayer interferential filters between both single-mode input and output fibers. With an ordinary personal computer, this method affords accurate calculation of the absorption losses and the diffraction into the cladding modes of both fibers as well as the reflectance into the input fiber. The calculation results show that absorption losses and diffraction are troublesome for high-finesse FP filters.

Investigation on the Insertion Loss of fiber Fabry-Perot filter with a bidirectional beam propagation method

“…We assume that the input and output fibers have a core diameter of 8μm, cladding diameter of 80μm, which is smaller than the actual value 125μm, then all the cavity energy can be regarded as being restricted in our simulation region [4] , and the core refractive index of n co is 1.49, cladding refractive index of n cl is 1.4859396, cavity refractive index of n 0 in the air gap is 1. We also assume that the mirrors are composed of alternately high refractive index layers (n H ) films and low refractive index layers (n L ) films, the physical thicknesses of the layers are corresponding to quarter wavelength optical thickness at a central wavelength.…”