Two types of emitting centers in Cr-doped Y2SiO5 laser crystals

Abstract

Chromium-doped forsterite and YAG have been shown to be efficient laser materials for the near-infrared. The lasing centers were described as Cr4+ ions occupying tetrahedrally coordinated positions. Recently, laser action in Cr4+:Y2SiO5 was demonstrated at low temperatures1 and at room temperature.2 One of the most interesting features of this new laser material is the dependence of output spectra on the pump wavelength.1 Moreover, luminescence properties of the Cr: Y2SiO5 were studied in Refs. 3 and 4, but the origin of the second emission, clearly observed at low temperatures, was not determined. In this paper we discuss the spectroscopic properties of tetravalent chromium in two silicates Y2SiO5 (YSO) and Gd2SiO5 (GSO). The results of polarized optical absorption, emission, and lifetime measurements are presented.