The observation of electron trap liberation in MgF$_{2}$ doped with Yb$^{2+}$ using a two-color excitation experiment

TL;DR

This study uses two-color excitation to observe electron trap liberation in MgF$_{2}$ doped with Yb$^{2+}$, revealing shallow traps around 17 cm$^{-1}$ and supporting a Coulomb trap model.

Contribution

First direct observation of electron trap liberation in MgF$_{2}$ doped with Yb$^{2+}$ using a two-color optical experiment.

Findings

Shallow traps with a depth of approximately 17 cm$^{-1}$ were liberated.

Photoluminescence enhancement was observed upon infrared excitation.

Results support a Coulomb trap model for electron trapping.

Abstract

We utilize the optical transitions of Yb$^{2+}$ excited by an ultraviolet optical parametric amplifier to probe electron trap liberation in MgF$_{2}$ via the observation of a photoluminescence enhancement effect induced by a subsequent infrared pulse from a free-electron laser. The temperature dependence of the enhancement suggests that we liberate very shallow traps having a depth of approximately 17 cm$^{-1}$. The observed `trap spectrum' is consistent with a simple model of a Coulomb trap.