Record fifth-harmonic-generation efficiency producing 211 nm, joule-level pulses using cesium lithium borate

The fifth harmonic of a pulsed Nd:YLF laser has been realized in a cascade of nonlinear crystals with a record efficiency of 30%. Cesium lithium borate is used in a Type-I configuration for sum-frequency mixing of 1053 and 266 nm, producing 211 nm pulses. Flat-topped beam profiles and pulse shapes optimize efficiency. The energies of the fifth harmonic up to 335 mJ in 2.4 ns pulses were demonstrated.