Tens of milliwatts CW 213 nm generation for photoemission spectroscopy

High power Continuous-Wave (CW) DUV lasers are required for high-resolution laser-based angle-resolved photoemission spectroscopy. This technique provides direct observations of band structures and is utilized to study quantum solid states. We realized a high-power 213 nm coherent light source based on fourth harmonic generation of an 852 nm laser for this purpose. Because we have placed importance on its reliability and long-term operation, we use a home-made nonlinear element and a Voice Coil Motor (VCM) cavity locker. We obtained a highest laser power of more than 270 mW and kept the laser power at 50 mW for long-period operation.