Generation of tunable radiation below 2000 Å by phase-matched sum-frequency mixing in KB5O8⋅4D2O

Abstract
We have investigated second harmonic generation(SHG) and sum‐frequency mixing (SFG) in deuterated potassium pentaborate using N2 laser pumped dye lasers. The crystal 90° second harmonic generates at 2161.5 Å with a power conversion efficiency of 5% at an input power of 15 kW. Tunable phase‐matched VUV SFG is observed from 2161.5 to 1962.4 Å. Transmission and birefringencemeasurements indicate that the crystal can phase match with high conversion efficiencies to below 1700 Å.