The effect of polarization on the propagation distance of leaky guided modes

TL;DR

This paper demonstrates that TM leaky modes can travel farther than TE modes in dielectric waveguides, with isolated resonances explained via a Schrödinger-type model, impacting mode filtering and information transfer.

Contribution

It introduces a theoretical framework explaining the extended propagation of TM modes using a Schrödinger-type equation and identifies the role of interface barriers.

Findings

TM modes propagate further than TE modes in certain waveguides.

Isolated peaks in TM spectrum are due to interface barriers.

The theory aids in mode filtering and optical communication applications.

Abstract

We show that transverse-magnetic (TM) leaky modes can propagate further than transverse electric (TE) modes in real-index dielectric waveguides. We compute the density of states and find that while the TE spectrum contains only overlapping resonances, the TM spectrum typically contains several isolated peaks. By transforming the TM equation into a Schr\"{o}dinger-type equation, we show that these isolated peaks arise due to $\delta$-function barriers at the core-cladding interface. Our theory is useful for a range of applications, including filtering TM modes from initially unpolarized light and transferring information between distant waveguides.