Laser gain characterization and CW laser operation in Nd:CaF2 co-doped with Gd3+ and Y3+ buffer ions

Abstract

The laser transition at 1.05μm of Nd³⁺:CaF₂, known to be quenched because of cross-relaxation energy transfers among Nd³⁺ ions, can lead to laser operation by codoping Nd3+ with optically inactive buffer ions, such as gadolinium and yttrium. This codoping enables a fine tailoring of the laser crystal spectroscopic properties depending on the nature and the concentrations of the co-dopants. We present in this work the investigation of laser gain measurements and its detailed characterization using a CaF2:0.5%Nd, 2.5%Gd,2.5%Y crystal, obtaining a laser amplification of 25% in small signal conditions with 800mW of pump power. Continuous wave (CW) laser action is also achieved with the same crystal leading to a 46% slope efficiency with respect to the absorbed pump power using an 8% output coupler transmission. The tunability of this laser crystal is also investigated from 1048 to 1072 nm for different pump wavelengths showing a flat spectral profile around 1052 nm. All these results show that this type of crystal is appealing for high peak power diode-pumped amplifiers and ultrashort pulse generation.