Damage-free finishing of Lu2O3 by combining plasma-assisted etching and low-pressure polishing

Abstract

Lutetium oxide (Lu2O3) is suitable for high-power laser matrices because of its excellent properties. However, the poor machinability greatly limits its practical applications. This work focuses on highly efficient and subsurface damage (SSD)-free machining of Lu2O3 using a new method, namely, plasma-assisted etching, followed by low-pressure polishing. An atomically smooth and SSD-free Lu2O3 surface is achieved with a surface roughness of 0.47 nm in Sa in 45 min. Experimental results show the laser fluence is significantly increased from 8.36 mJ/mm2 by 80 min of conventional polishing to 17.84 mJ/mm2 by the proposed approach, benefiting various applications in laser systems.