Engineering Interaction Dynamics in Active Resonant Photonic Structures

TL;DR

This paper demonstrates how to engineer asymmetric interaction dynamics in active resonant photonic structures using non-Hermitian concepts, enabling new phenomena like phase locking and topological effects in photonic lattices.

Contribution

It introduces a generalized photonic molecule with tunable Hermitian and non-Hermitian interactions, advancing the control of interaction dynamics in integrated photonic systems.

Findings

Experimental realization of Hermitian and non-Hermitian coupling in microring resonators

Observation of tailored exchange interactions affecting phase locking

Potential for implementing non-Hermitian topological phenomena

Abstract

The collective response of a system is profoundly shaped by the interaction dynamics between its constituent elements. In physics, tailoring these interactions can enable the observation of unusual phenomena that are otherwise inaccessible in standard settings, ranging from the possibility of a Kramer's degeneracy even in the absence of spin to the breakdown of the bulkboundary correspondence. Here, we show how such tailored asymmetric coupling terms can be realized in photonic integrated platforms by exploiting non-Hermitian concepts. In this regard, we introduce a generalized photonic molecule composed of a pair of microring resonators with internal S-bends connected via two directional couplers and a link waveguide. By judiciously designing the parameters of this system, namely the length of the links and the power division ratio of the directional couplers, we experimentally show the emergence of Hermitian and non-Hermitian type exchange interactions. The ramifications of such coupling dynamics are then studied in 1D chain and ring-type active lattices. Our findings establish the proposed structure as a promising building block for the realization of a variety of phenomena, especially those associated with phase locking in laser arrays and non-Hermitian topological lattices.