The infinity-loop microresonator: A new integrated photonic structure working on an exceptional surface

Abstract

Exceptional points, where eigenvalues and eigenvectors coalesce, impact the behavior of different photonics components that show, e.g., enhanced sensing, coherent perfect absorption, unidirectional lasing, and chirality. However, only a few passive geometries have been developed that work on these points. Here, we introduce a novel non-Hermitian structure based on a microresonator shaped as the infinity symbol twice coupled to a bus waveguide: the infinity-loop microresonator. Unlike other structures working on an exceptional surface, the infinity-loop microresonator can achieve either high- or low-contrast unidirectional reflection with a negligible or identical reflection for counterpropagating light. It allows an easy walking through the Riemann sheet by simply controlling the phase of the light propagating in the bus waveguide, which makes it a tunable component to build more complex topological structures. Furthermore, the infinity-loop microresonator allows sensors that show the features of both an exceptional point device and a diabolic point device simultaneously.

14 pages, 12 figures

References in corpus (5)

• The physics of exceptional points
• What is- and what is not- Electromagnetically-Induced-Transparency in Whispering-Gallery-Microcavities
• Observation of coherent perfect absorption at an exceptional point
• Linear response theory of open systems with exceptional points
• Influence of the bus waveguide on the linear and nonlinear response of a taiji microresonator