Signature of femtosecond laser-induced superfluorescence from atomic hydrogen

Cavity-free lasing generation from gas constituents has been studied in the past decade since it promises great potentials in remote sensing and optical diagnostics techniques. Here we report on experimental investigations of temporal characteristics of H-atom lasing emission at 656 nm by examining the dependences of its durations and delays on the pump-laser-pulse energies. An indirect measurement was also performed to test the delays of the lasing pulse for varying H-atom concentrations. The results show that the lasing pulse exhibits considerable superfluorescence signatures. Analysis based on experimental parameters by using deductive expressions of superfluorescence theory shows good agreement to this conjecture. Our investigations on fundamentals could pave the way to a better understanding of the lasing generation and further applications of lasing-based optical diagnostics.