Generation of air lasing at extended distances by coaxial dual-color femtosecond laser pulses

Abstract

We present an approach for generation of air lasing at extended distances by coaxial dual-color femtosecond laser pulses. A strong 800 nm pulse prepares the population inversion in during the filamentation in air, and a weak 400 nm pulse produced coaxially with the 800 nm light by frequency doubling in a BBO crystal seeds the gain medium, producing strong narrow-band lasing emission at ∼391 nm. We demonstrate that this scheme can overcome the difficulty in spatially overlapping two beams at a far distance, and the lasing emissions at a designed position can be manipulated by dispersion components inserted in the propagation path of the coaxial two-color beam. Our results provide a way for remote generation of air laser for standoff spectroscopy and detection.