On-chip 7 GHz acousto-optic modulators for visible wavelengths

TL;DR

This paper reports the development of a compact, high-frequency acousto-optic phase modulator for visible wavelengths on a lithium niobate platform, enabling efficient modulation and potential quantum photonic integration.

Contribution

The paper introduces a 7 GHz on-chip acousto-optic modulator for visible light using a lithium niobate on sapphire platform, demonstrating high efficiency and novel single-sideband modulation effects.

Findings

Achieved phase modulation within 200 microns device length

Observed single-sideband modulation due to acoustic wavelength matching optical wavelength

Showed potential for integration with quantum photonic systems

Abstract

A chip-integrated acousto-optic phase modulator tailored for visible optical wavelengths has been developed. Utilizing the lithium niobate on sapphire platform, the modulator employs a 7 GHz surface acoustic wave, excited by an interdigital transducer and aligned perpendicular to the waveguide. This design achieves efficient phase modulation of visible light within a compact device length of merely 200 microns, while holds the advantages of easy fabrication and high stability due to simple unsuspended structure. Remarkably, in this high-frequency acoustic regime, the acoustic wavelength becomes comparable to the optical wavelength, resulting in a notable single-sideband modulation behavior. This observation underscores the phase delay effects in the acousto-optics interactions, and opens up new aspects for realizing functional visible photonic devices and its integration with atom- and ion-based quantum platforms.