In-Depth Determination of the Microstructure and Energy Transition Mechanism for Nd3+-Doped Yttrium Oxide Laser Crystals

Abstract

Rare-earth Nd3+-doped yttrium oxide (Y2O3) is an important near-infrared (NIR) laser material with good chemical and thermal stability. However, the microstructure and energy transition mechanism of Nd3+-doped Y2O3 remains challenging. Herein, we report a systematic study on the microstructure and energy transition of Nd3+-doped Y2O3 by unbiased CALYPSO structural search and our newly developed WEPMD method. A new monoclinic structure with P2 space group symmetry is identified. It is shown that the doped Nd3+ ion exactly substitutes the Y3+ ion in the host crystal, resulting in the decrease of the energy band gap of Y2O3. Based on the Judd–Ofelt theory, a large number of energy transitions are predicted at the NIR region. The results indicate that the energy transition of 2H(2)11/2 → 4I15/2 is about 1033 nm, which makes it a good candidate for laser action. Three important absorption lines from 4I9/2 to 2H(2)11/2, 4G5/2, and 2G(1)7/2, at approximately 600 nm and indistinguishable by experiment, are uncovered for the first time. The present findings enrich the fundamental understanding of the Nd:Y2O3 crystal and will help advance the rational design of a new type of laser device.