Tianyuan Zhou

Energy level systems and transitions of Ho:LuAG laser resonantly pumped by a narrow line-width Tm fiber laser

We presented a Ho:LuAG ceramic laser in-band pumped by a narrow emission line-width Tm fiber laser at 1907 nm. All of potential transitions between 5I7 and 5I8 manifold were discussed to form the Hos in-band-pump energy level systems, which were not described in details earlier. For the emission band centered at ~2095 nm, both laser absorption and emission transition separately consisted of two groups were first analyzed and observed. Using output couplers (OCs) with different transmittances (T = 6, 10 and 20%), the similar ~0.5 W continuous-wave (CW) output power under an incident pump power of ~4.9 W was obtained, with twin (or triplet) emission bands respectively. The blue shift of center emission wavelengths was observed with the increase of transmittances.

Preliminary study of 3D ball-milled powder processing and SPS-accelerated densification of ZnSe ceramics

Spark plasma sintering (SPS) was utilized to achieve the densification of ZnSe ceramics with a simple 3D ball-milling powder processing. The morphology evolution of powders during the ball milling process and the densification and microstructure of fabricated ceramics were investigated. The effective ball-milling of 8h obviously reduced the particle size and the full densification of ZnSe ceramics was achieved at the sintering temperature of 900 °C. The lower heating rate could obtain the denser ceramics with fewer pores and fine microstructure but serious carburization, and higher heating rate accelerated the grain growth. The optimized heating rate of 5 °C/min obtained the fine grain size of ~5.0 μm. Some challenging issues of fundamentals and technologies were proposed to improve the optical quality of ZnSe ceramics by SPS.