Spectroscopic investigations of a Ti:Tm:LiNbO3 waveguide for photon-echo quantum memory

TL;DR

This study fabricates and characterizes a Ti:Tm:LiNbO3 waveguide, revealing key optical properties and coherence times crucial for developing integrated photon-echo quantum memory devices.

Contribution

It provides detailed spectroscopic data and demonstrates the waveguide's potential for quantum memory applications, including coherence times and Stark shift measurements.

Findings

Radiative lifetimes of 82 μs and 2.4 ms for specific levels

Optical coherence time of 1.6 μs at 795 nm

Persistent spectral holes with lifetimes up to seconds

Abstract

We report the fabrication and characterization of a Ti$^{4+}$:Tm$^{3+}$:LiNbO$_3$ optical waveguide in view of photon-echo quantum memory applications. In particular, we investigated room- and cryogenic-temperature properties via absorption, spectral hole burning, photon echo, and Stark spectroscopy. We found radiative lifetimes of 82 $\mu$s and 2.4 ms for the $^3$H$_4$ and $^3$F$_4$ levels, respectively, and a 44% branching ratio from the $^3$H$_{4}$ to the $^3$F$_4$ level. We also measured an optical coherence time of 1.6 $\mu$s for the $^3$H$_6\leftrightarrow{}^3$H$_4$, 795 nm wavelength transition, and investigated the limitation of spectral diffusion to spectral hole burning. Upon application of magnetic fields of a few hundred Gauss, we observed persistent spectral holes with lifetimes up to seconds. Furthermore, we measured a linear Stark shift of 25 kHz$\cdot$cm/V. Our results are promising for integrated, electro-optical, waveguide quantum memory for photons.