Аннотация:The parametric down conversion of high intensity femtosecond laser pulses is discussed. An injection-locked parametric oscillator, based on a new nonlinear crystal LBO is presented. With 1 mJ, 400 fs pump pulses we observe 25% quantum efficiency. With the injection at lambda = 1.08 mum the oscillator is tuned throughout the range 1.2-1.5 mum by changing the pump frequency from 0.57 to 0.63 mum. The surface breakdown threshold of LBO was measured to be 3.5.10(13)W/cm2 for 400 fs pulses