Laser-based studies of nonradiative dynamics in neodymium-doped crystals

J. Boyden, G.L. Clark

A.A. Kamarzin, A. A. Mamedov, Valerii A Smirnov +2 more

An investigation is made of processes of population and relaxation of the 4F3/2 neodymium upper active level in a γ-La2S3 semiconductor single crystal and the energy transfer microparameters are determined. Nonradiative transfer of energy from a continuous set of traps to the 4F3/2 upper active level of neodymium was observed when the sample was excited with λ = 0.53 μ radiation and cross relaxation from excited states located above the 4F3/2 upper active level was identified.

Guangming Wang

A. Brignon, Jean‐Pierre Huignard

Degenerate four-wave mixing (DFWM) interaction in saturable media has received considerable attention because of its potential for application to optical phase conjugation and correction of phase distortions through aberrating media. For this purpose, saturable solid-state materials, operating at the classical wavelength of neodymium lasers near λ0 = 1.06 μm, are of great interest. Here, we present DFWM in a tetravalent chromium-doped gadolinium-scandium-gallium-garnet (Cr4+:GSGG) crystal. Indeed, tetravalent chromium (Cr4+) doped crystals were recently shown to be effective solid-state saturable absorbers for neodymium lasers.1,2 Furthermore, in comparison with traditional saturable absorbers such as dyes in solution, polymeric films, and color-center materials, these crystals exhibit chemical stability, high optical damage threshold, compactness, and would enable operation at high repetition rates.

Matthew J. Sellars

Emmanuel Zambrini Cruzeiro

Spin dynamics are investigated in several rare-earth-ion-doped crystals, both for so-called Kramers ions and non-Kramers ions. I have studied two illustrative examples of such systems, Neodymium (Kramers) and Europium (non-Kramers). The main motivation behind these studies is the search for long relaxation and coherence times in solid state atomic ensembles. To this end I employ spectroscopic techniques to probe different kinds of interactions and relaxation mechanisms taking place in the samples. I perform spectroscopy of Neodymium (Kramers) in two different crystal lattices, yttrium orthosilicate and yttrium orthovanadate. I propose new methods to improve the relaxation lifetimes, and make precise characterizations of the interactions taking place within the atomic ensemble. In particular we achieve the most precise measurement of a kind of interaction which has received considerable attention recently in other areas of physics, the Dzyaloshinskii-Moriya interaction. These spectroscopic studies are of course of fundamental interest, but they can also be applied to quantum communication and computation. In this context, we were able to increase the efficiency of a quantum memory based on a Kramers ion (Nd) to be on par with the best non-Kramers (Eu,Pr) memories. Using Neodymium ions, I have certified that multi-dimensional entanglement can be stored in a quantum memory. The second part of this thesis concerns the study of Europium (non-Kramers), starting with a characterization of the Zeeman and quadrupole interactions. I believe these studies will pave the way for long duration (100 ms or more) quantum storage in a rare-earth-ion-doped crystal.