On the use of the Fourier modal method for calculation of localized eigenmodes of integrated optical resonators

TL;DR

This paper extends the Fourier modal method to compute localized eigenmodes in integrated optical resonators by analyzing the poles of the structure's scattering matrix, enabling better design of optical and plasmonic devices.

Contribution

The paper introduces a generalized Fourier modal method that calculates complex eigenfrequencies and field distributions of localized modes via analytic continuation of the scattering matrix.

Findings

Calculated eigenmodes of dielectric blocks on metal surfaces.

Resonant features observed in SPP transmission spectra.

Method applicable for designing integrated optical devices.

Abstract

We propose the generalization of the Fourier modal method aimed at calculating localized eigenmodes of integrated optical resonators. The method is based on constructing the analytic continuation of the structure's scattering matrix and calculating its poles. The method allows one to calculate the complex frequency of the localized mode and the corresponding field distribution. We use the proposed method to calculate the eigenmodes of rectangular dielectric block located on metal surface. We show that excitation of these modes by surface plasmon-polariton (SPP) results in resonant features in the SPP transmission spectrum. The proposed method can be used to design and investigate optical properties of integrated and plasmonic optical devices.