Title: Sesquioxide transparent laser ceramics: The current status

Abstract

Sesquioxide crystals, such as Y2O3, Lu2O3 and Sc2O3, have cubic crystal structure, relatively high thermal conductivity, small thermal expansion coefficient and small phonon energy. They are considered as a desired host material for high power solid state laser applications. However, the growth of sesquioxide single crystals is very difficult due to their extremely high melting points (>2400°C). In this talk, we will present our fabrication process for transparent sesquioxide (Y2O3 and Lu2O3) ceramics with optical quality comparable to single crystals. Rare earth ions doped Y2O3or Lu2O3raw powders were synthesized by using a chemical co precipitation method. The powders synthesized in house have high purity (>99.995%) and narrow particle size distribution. The ceramics were first densified in vacuum and then post treated with a hot isostatic presser (HIP) at below 1600°C, which is only two-thirds of their melting temperature. A series of rare-earth doped sesquioxide-based laser ceramics, such as Yb3+:Y2O3, Yb3+:Lu2O3, Nd3+:Y2O3, Ho3+:Y2O3, Er3+:Y2O3, Dy3+:Y2O3,Pr3+:Y2O3 and Cr4+/2+:Y2O3 were fabricated. The fabricated laser ceramics have very good optical homogeneity and high in-line transmittance. The in-line transmittance of a fabricated Yb:Y2O3 laser ceramic in the wavelength range from 400 nm to 6μmis. High power high efficiency laser operations of the fabricated laser ceramics at 1.0µm, 2.1µm, and 2.7µm have been successfully demonstrated, respectively. Potential applications of Y2O3 transparent ceramics for laser oscillations in the visible and > 3.0µm wavelengths are also explored.