Multiplexing Guided Optical and Acoustic Waves for Efficient Acousto-Optic Devices

TL;DR

This paper introduces an acoustic-optical multiplexer that enables co-propagation of light and sound in integrated devices, enhancing photon-phonon interactions for efficient acousto-optic applications.

Contribution

It presents the first design of a multiplexer that combines optical and acoustic modes into a single co-guided output, facilitating broadband, integrated acousto-optic devices.

Findings

Simulations demonstrate low insertion loss and reflection.

The multiplexer enables efficient photon-phonon interactions.

Design is compatible with silicon and silica beams.

Abstract

Acousto-optic devices utilize the overlap of acoustic and optical fields to facilitate photon-phonon interactions. For tightly confined optical and acoustic fields, such as the sub-wavelength scales achievable in integrated devices, this interaction is enhanced. Broadband operation which fully benefits from this enhancement requires light and sound to co-propagate in the same cross-section, a geometry currently lacking in the field. We introduce the `acoustic-optical multiplexer', which enables this co-linear geometry, and demonstrate through simulations a proof-of-concept design. Using suspended silicon and silica beams, the multiplexer combines two optical modes and an acoustic mode into a single, co-guided output port with low insertion loss and reflection for both optics and acoustics. The first design in its class, the multiplexer enables integrated acousto-optic devices to achieve efficient photon-phonon interactions.