Development of Nd-doped Optical Gain Material Based on Silica Glass with High Thermal Shock Parameter for High-Average-Power Laser

Abstract

In this paper, we report a demonstration of amplification at 1.06 µm in a bulk-type Nd-doped silica glass (Nd2O3: 1.25 wt%, Al2O3: 2.72 wt%, SiO2: 96.03 wt%) with a high thermal shock parameter for the first time. The optical gain of 1.75 was obtained in a 93-mm-long sample with a flash lamp pumping at 1.9 kJ, corresponding to a gain coefficient of 0.06 cm-1. The thermal shock parameter of Nd-doped silica glass was measured to be 12.0 W/cm, which is thirty times greater than that of phosphate glass and one and a half times greater that of Nd:YAG. We carried out a quick quenching experiment to determine the thermal shock toughness of Nd-doped silica glass, and the experiment demonstrated that the thermal shock toughness of Nd-doped silica glass was superior to that of the phosphate laser glass. We also calculated the thermal stress distribution in Nd-doped silica glass with a simple model for comparison with the experimental results; the model well explains the experimental results. These results indicate that Nd-doped silica glass can produce a compact, high-energy density, and high-average-power laser.