Calculation, normalization and perturbation of quasinormal modes in coupled cavity-waveguide systems

TL;DR

This paper introduces a method using non-local boundary conditions for calculating quasinormal modes in coupled cavity-waveguide systems, extending the mode norm definition to model optical phenomena and analyzing perturbations in resonance frequency and Q factor.

Contribution

It presents a novel approach for computing quasinormal modes with compatible boundary conditions and extends the mode norm framework using divergent series theory.

Findings

Effective calculation of quasinormal modes in coupled systems

Framework for modeling optical phenomena with extended mode norm

Analysis of perturbative changes in resonance frequency and Q factor

Abstract

We show how one can use a non-local boundary condition, which is compatible with standard frequency domain methods, for numerical calculation of quasinormal modes in optical cavities coupled to waveguides. In addition, we extend the definition of the quasinormal mode norm by use of the theory of divergent series to provide a framework for modeling of optical phenomena in such coupled cavity-waveguide systems. As an example, we apply the framework to study perturbative changes in the resonance frequency and Q value of a photonic crystal cavity coupled to a defect waveguide.