Observation of collision induced processes in rubidium-ethane vapour

The collision-induced stimulated resonant emission on 5(2)P(1/2)-5(2)S(1/2) transition in rubidium vapour in the presence of ethane as a buffer gas is measured. This effect is investigated experimentally and analyzed theoretically in the small gain approximation. Within this approximation, the main differences between the generation of collision induced amplified spontaneous emission (ASE) signal in cesium-ethane, rubidium-ethane and sodium-ethane mixture were estimated. The dependencies of the ASE intensity on the energy of the laser pump and ethane pressure are measured and the efficiency of the ASE signal generation as a function of the exciting energy is given. The model of longitudinally pumped alkali metal-molecular gas amplifier was developed in order to explain the unusual behaviour of the dependence of the efficiency of the ASE signal generation in the rubidium-ethane mixture on the Gaussian pump beam exciting energy. Some analogies with erbium and ytterbium doped fiber amplification processes are given. (C) 1999 Elsevier Science B.V. All rights reserved.