Interaction between a Waveguide Mode and an Absorptive Medium

TL;DR

This paper introduces a new formulation for the interaction factor in waveguide-based absorption spectroscopy, showing its inverse proportionality to the waveguide mode's energy velocity, which enhances understanding of wave-medium interactions.

Contribution

A novel mathematical formulation for the interaction factor in waveguide absorption spectroscopy, linking it to the energy velocity of the waveguide mode.

Findings

Interaction factor is inversely proportional to energy velocity.

New formulation improves understanding of waveguide-medium interactions.

Potential to optimize waveguide design for spectroscopy applications.

Abstract

Absorption spectroscopy studies the absorption of electromagnetic wave in a material sample under test. The interacting electromagnetic wave can be propagating in free space or in a waveguide. The waveguide-based absorption spectroscopy method has several advantages compared to the free space setup. The effect of the waveguide cross section on the interaction between the waveguide mode and the sample can be expressed by a factor, called interaction factor. In this article, a new formulation for the interaction factor is derived. It is shown that this factor is inversely proportional to the energy velocity of the waveguide mode.