Picosecond two-dimensional “halo” superradiance and laser in rhodamin 6G

Two-dimensional “halo” superradiance and laser operation has been induced in Rhodamin 6G dye by picosecond pulse excitation. At single pulse excitation under special pumping conditions a 30 ps merging superradiation propagating simultaneously in every direction of the plane was observed. In the case of pulse train excitation, contrary to the general observations made on conventional “one-dimensional” lasers, the duration of the thus obtained laser radiation was found to be longer by two orders of magnitude than of the excitation and to increase from pulse to pulse in the train.