A chip-integrated coherent photonic-phononic memory

TL;DR

This paper demonstrates a chip-integrated coherent photonic-phononic memory capable of storing and retrieving optical signals with GHz bandwidth in an integrated waveguide, enabling multi-wavelength operation with minimal cross-talk.

Contribution

It introduces a novel integrated planar optical waveguide memory that coherently transfers optical information to acoustic hypersound waves for high-bandwidth storage.

Findings

Achieved GHz-bandwidth optical storage and retrieval.

Demonstrated operation at multiple wavelengths with negligible cross-talk.

Showed coherent transfer of phase and amplitude of optical signals.

Abstract

Controlling and manipulating quanta of coherent acoustic vibrations - phonons - in integrated circuits has recently drawn a lot of attention, since phonons can function as unique links between radiofrequency and optical signals, allow access to quantum regimes and offer advanced signal processing capabilities. Recent approaches based on optomechanical resonators have achieved impressive quality factors allowing for storage of optical signals. However, so far these techniques have been limited in bandwidth and are incompatible with multi-wavelength operation. In this work, we experimentally demonstrate a coherent buffer in an integrated planar optical waveguide by transferring the optical information coherently to an acoustic hypersound wave. Optical information is extracted using the reverse process. These hypersound phonons have similar wavelengths as the optical photons but travel at 5-orders of magnitude lower velocity. We demonstrate the storage of phase and amplitude of optical information with GHz-bandwidth and show operation at separate wavelengths with negligible cross-talk.