Parametric generation of picosecond light pulses with an energy conversion greater than 50 %

Coordinated theoretical and experimental investigations were made of the conditions for achieving high energy exchange in three-wave parametric interaction of temporally and spatially modulated picosecond light packets. An efficiency of $\gtrsim$ 50 % was achieved for conversion of pump energy into radiation with continuously tunable wavelengths under optimal conditions in a KDP crystal. In this case, a spatial pump-radiation profile without random amplitude-phase distortions was an extremely important factor.