Nd,Y:CaF2 laser crystals: novel spectral properties and laser performance from a controlled local structure

Abstract

A series of Nd,Y:CaF₂ single crystals grown using the TGT method were studied systematically by absorption, excitation and luminescence spectroscopy, and the extended X-ray absorption fine structure (EXAFS) technique. The incorporation of Y³⁺ substantially manipulated the local structure of Nd ions in the CaF₂ crystal lattice. Subsequently, the changes in the local structure of the Nd³⁺ ions induced substantial variations of the photoluminescence parameters, including FWHM, cross sections, lifetimes and quantum efficiency. Preliminary laser experiments were carried out with 0.5% Nd,10% Y:CaF₂, 0.8% Nd,5% Y:CaF₂ and 0.8% Nd,10% Y:CaF₂ crystals under LD pumping; true CW laser operation was achieved with slope efficiencies of 30.1%, 19.3% and 24.9%, respectively.