Simple two-step photoionization yields high densities of laser-active <i>F</i>2+ centers

Abstract

A selective two-step process is described for the photoionization of F2 centers. An electron trap density no greater than that of the original F2 center population is required for ∼100% ionization, and only modest light intensities are required (I∼10 W/cm2 or less). Certain divalent transition-metal ions have been found to make excellent traps. The two-step process has allowed the production of F+2 center densities ∼1018/cm3, as needed for the construction of efficient lasers.