An Integrated Optical Memory based on Laser Written Waveguides

TL;DR

This paper demonstrates the first integrated optical memory using laser written waveguides in a doped crystal, enabling enhanced light-ion interaction and on-demand quantum memory capabilities.

Contribution

It introduces a novel laser micromachining technique to create waveguides in Pr$^{3+}$:Y$_2$SiO$_5$ crystals without degrading coherence, advancing integrated quantum memory technology.

Findings

Waveguides increase light-ion interaction by a factor of 6.

Optical pumping protocols are successfully implemented in waveguides.

First realization of laser written waveguides in Pr$^{3+}$:Y$_2$SiO$_5$.

Abstract

We report on the first realization of an integrated optical memory for light based on a laser written waveguide in a doped crystal. Using femto-second laser micromachining, we fabricate waveguides in Pr$^{3+}$:Y$_2$SiO$_5$ crystal. We demonstrate that the waveguide inscription does not affect the coherence properties of the material and that the light confinement in the waveguide increases the interaction with the active ions by a factor 6. We also demonstrate that, analogously to the bulk crystals, we can operate the optical pumping protocols necessary to prepare the population in atomic frequency combs, that we use to demonstrate light storage in excited and spin states of the Praseodymium ions. Our results represent the first realization of laser written waveguides in a Pr$^{3+}$:Y$_2$SiO$_5$ crystal and the first implementation of an integrated on-demand spin wave optical memory. They open new perspectives for integrated quantum memories.