Acoustically control of integrated optical microrings: from photonic molecule to Mobius strip

TL;DR

This paper demonstrates acoustic control over integrated optical microrings on a lithium niobate platform, enabling dynamic reconfiguration of photonic circuits and revealing topological transformations like Mobius strips.

Contribution

It introduces a novel method of using gigahertz acoustic waves to dynamically reconfigure optical paths and topologies in integrated photonic circuits.

Findings

Achieved strong coupling of supermodes with milliwatt power

Created a dynamic Bragg mirror within optical paths

Observed topological transformation towards Mobius strip

Abstract

Microring resonators (MRRs) are fundamental building blocks of photonic integrated circuits, yet their dynamic reconfiguration has been limited to tuning refractive index or absorption. Here, we demonstrate acoustic control over optical path topology on a lithium niobate on sapphire platform. By launching gigahertz acoustic waves into a hybrid phononic-photonic waveguide, a dynamic Bragg mirror (DBM) is created within the optical path, coupling forward and backward propagating light. Employing a pair of coupled MRRs, we achieve strong coupling between supermodes of the photonic molecule with only milliwatt-level drive power, yielding a cooperativity of 2.46 per milliwatt. At higher power, DBM reflectivity up to 24% is achieved, revealing breakdowns of both the photonic molecule picture and perturbative coupled mode theory, indicating the transformation toward Mobius strip topology. Our work establishes a new dimension for controlling photonic devices, opening pathways toward fully reconfigurable photonic circuits through acoustic drive.