Effects of Neodymium Concentration on Optical Characteristics of Polycrystalline Nd:YAG Laser Materials

TLDR

The authors fabricated Nd:YAG ceramics containing 0.3–4.8 at % Nd by solid‑state reaction and evaluated them in a continuous‑wave diode‑laser pumped laser oscillation experiment alongside a 0.9 at % Nd single crystal. The 2.4 at % Nd ceramic exhibited the highest fluorescence intensity, while its lasing threshold (356 mW) and slope efficiency (40 %) surpassed those of the 1.1 at % ceramic (309 mW, 28 %) and the 0.9 at % single crystal, indicating superior performance of the ceramics.

Abstract

A neodymium‐doped yttrium‐aluminum garnet (Y 3 A1 5 O 12 , YAG) (Nd:YAG) ceramic that contained 0.3–4.8 at.% neodymium additives and exhibited nearly the same optical properties as those of a single crystal was fabricated by a solid‐state reaction method using high‐purity powders. Although the integrated absorption intensity of the 2 H 9/2 + 4 F 5/2 bands simply increased as the neodymium concentration in the YAG ceramics decreased, the fluorescence intensity of the 2.4 at.% Nd:YAG ceramic was the strongest among Nd:YAG ceramics with various neodymium concentrations and a 0.9 at.% Nd:YAG single crystal. An oscillation experiment was performed on a continuous‐wave (cw) laser with a diode‐laser exciting system using those ceramics and the single crystal. The oscillation threshold and slope efficiency in that analysis were 309 mW and 28%, respectively, for the 1.1 at.% Nd:YAG ceramics and 356 mW and 40%, respectively, for the 2.4 at.% Nd:YAG ceramics. The lasing characteristics of the ceramics in the present work were superior to those of a 0.9 at.% Nd:YAG single crystal that was fabricated by the Czochralski (Cz) method.