Fabrication and thermal effects of highly transparent polycrystalline Nd: YAG ceramics

Highly transparent polycrystalline 2.0 at.% Nd:YAG ceramics were fabricated by a solid-state reactive sintering method using commercial alpha-Al2O3, Y2O3 and Nd2O3 powders as starting materials. The in-line transmittances of the Nd:YAG ceramics vacuum sintered at 1750 degrees C for 50 h with the thickness of 5.8 mm are 83.9% at 1064 nm and 82.5% at 400 nm. The thermal effects in the Nd:YAG ceramics were mainly investigated in detail. It is found that the thermal focal length decreases with the increase of pump power. The experimental results of thermal focal lengths are in accordance with the theoretical calculations. The observed depolarized beam patterns and depolarization phenomena illustrate the detailed change of thermally induced birefringence in Nd:YAG ceramics. The depolarization shows a obvious non-linear change tendency at low pump power. (C) 2015 Elsevier B.V. All rights reserved.