Modal cut of properties of a metal coated optical waveguide with trefoil cross-section under weak guidance approximation

Abstract

In the present paper the author investigated the propagation of electromagnetic wave through the special cross-sectional waveguide whose guiding region consist three cores embedded in common metallic boundary. By choosing an appropriate coordinate system, the scalar wave equation is solved, and thereby characteristic equation for the guided modes under the weak guidance approximation is derived using analytical method. To understand the basic modal properties in a simple manner, the cutoff equation is derived, and the modal cutoff properties of some lower order modes are determined numerically. The author also gave a comparative study of metallic boundary instead of dielectric cladding boundary on the modal cutoff behavior of waveguide.