Stimulated emission in aluminum laser-induced plasma: kinetic model of population inversion

摘要

The stimulated emission (SE) in aluminum laser-induced plasma pumped in resonance with the 3s(2)3p-3s(2)4s aluminum transition at 266.04 nm is modeled. A collisional-radiative plasma model based on kinetic equations is proposed to explain the creation of the population inversion and lasing. The model predicts fast depopulation of the ground 3s(2)3p state by the absorption of resonant laser light at 266 nm and very fast population of the excited 3s(2)4s state by the cascade transitions from the laser-pumped level, which is driven optically and by collisions. The SE of the 3s(2)3p-3s(2)4s transition at 396.15 nm is studied and possible SE at 1.3 and 2.1 mu m is predicted. It is confirmed by calculations that the population inversion between the 3s(2)3p and 3s(2)4s states can be created by weak pumping at several microjoule-millijoule pulse energies and results in high gain. (C) 2017 Optical Society of America