Abstract

The resonance absorption, for which the starting (lower) energy level is the excited state, occurs in an explosive form. In this case the absorption coefficient is close to zero when the radiation intensity is small. It jumps to an almost normal value when the radiation intensity exceeds the threshold value depending on temperature, rate of relaxation, and cross section of the absorption. The mechanism of the explosive absorption is based on the energy exchange between the energy levels of absorbing species (atoms, molecules, and so on).

© 1986 Optical Society of America