FEMTOSECOND TRAVELING-WAVE PARAMETRIC GENERATION WITH LITHIUM TRIBORATE

Ultrashort pulses, of the same time duration as the pump pulse, have b een obtained with a traveling-wave parametric generator employing a te mperature-tuned lithium triborate crystal in noncritical phase matchin g. Starting from a 190-fs pulse at 0.6 mum generated by a dye laser, w e achieved an overall conversion efficiency of 10-15% in the tuning ra nge 0.85-0.97 mum (and the corresponding range of 1.6-2.1 mum) with a pump energy of only 30 muJ. The easy operation in the femtosecond regi me and the minimal energy requirements that we found are due to the sm all group-velocity mismatch of lithium triborate at this pump waveleng th and to the absence of walk-off.