A new exceptional point condition for coupled microresonators with coupled mode theory in space

TL;DR

This paper derives new conditions for exceptional points in coupled microresonators using a spatial coupled mode theory, providing more accurate predictions and insights into parity-time symmetry effects.

Contribution

It introduces a spatial coupled mode theory approach to determine exceptional point conditions, improving accuracy over traditional time-based models.

Findings

Spatial coupled mode theory yields different EP conditions than time-based models.

Comparison of spectra shows significant deviations between models.

Provides practical guidance for designing coupled microrings at EPs.

Abstract

We derive new exceptional point (EP) conditions of the coupled microring resonators using coupled mode theory in space, a more accurate approach than the commonly used coupled mode theory in time. Transmission spectra around EPs obtained from the two models have been compared on two material platforms, revealing non-negligible deviations. Our analysis provides a guide for accurately determining parameter sets of coupled microrings at EPs and deepens our understanding on parity-time-symmetric coupled resonators at EPs.