Optical superradiance in Van-Vleck paramagnets

Abstract

The paper describes experimental investigations of two-color optical super-radiance (SR) in LaF3:Pr3+ crystal. Optical excitation was made on the transition 3P0- 3H4(0) at liquid helium temperature. When the power of the pumping 10ns-pulse was higher than a certain threshold, the resonant medium emitted an optical SR pulse on 3P0-3H4(0) transition with a duration of 8-10 ns in the direction of the pumping pulse delayed in time by 12-15 ns with respect to the pumping pulse. When the peak power of the pumping pulse increases up to 40 kW, an SR pulse was also observed for the 3P0-3H6(1) transition. The delay time of this pulse was about 30 ns. Thus, the two-color SR in the employed crystal was observed.