The observation of electron trap liberation in MgF${}_2$ doped with Yb${}^{2+}$ using a two-color excitation experiment

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.