Optical superradiance in Van-Meek paramagnets

摘要

The paper describes experimental investigations of two-colour optical superradiance (SR) in LaF_3:Pr~(3+) crystal. Optical exciation was made on the transition ~3P_0―~3H4(0) (wavelength 477.7 nm) at liquid helium temperature. When the power of the pumping 10ns-pulse was higher than a certain threshold (～10 kW), the resonant medium emitted an optical SR pulse on ~3P_0―~3H_4(0) transition with a duration of 8-10 ns in the direction of the pumping pulse (as well as in the opposite direction) 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 ~3P_0―~3H_6(1) transition. The delay time of this pulse was about 30 ns. Thus, the two-color SR in the employed crystal was observed.