Analysis of cut-off conditions for coaxial fibers

This paper reports the analysis of modal normalized frequency cut-off of coaxial fibers having four dielectric layers. The cut-off curves are obtained for four different structures and several modes as a function of the several parameters of the fibers (refractive index and layer dimension). The calculation is done using a transcendental equation obtained in this work. The analysis pays a special attention to the fundamental mode HE11 showing that for two structures (W1 and M1) the normalized frequency always is null as is the case of the standard rod fibers. For the other two structures (W2 a...