Modal cutoff behavior of an optical waveguide with a multiloop core cross section embedded in a common cladding

Abstract

In this paper, a multiloop curve with a rather simple mathematical description in polar coordinates is chosen to describe the core cross-section boundary of a waveguide. This waveguide is used as a model representing a waveguide in which several cores are embedded in a common cladding. The cutoff equation for the lowest order modes is derived using the scalar wave approximation. Numerical computations are made to determine how the cutoff condition is modified as one increases the number of cores (loops) from three to ten. It is found that a waveguide with a cross section having fewer loops sustains more modes than that with a greater number of loops.