56 kW peak power, nanosecond pulses at 274 nm from a frequency quadrupled Yb-doped fiber MOPA

(BBO) crystal in sequence, with an IR-to-green and green-to-UV conversion efficiency of up to 65% and 26%, respectively. This is the first kW peak power pulsed UV system reported at 274 nm which has great potential for machining insulators, 2D materials, isotopic separation of Calcium-48, and fluorescence analysis of biological molecules.