EFFECT OF SPATIAL OVERLAP IN OPTICALLY PUMPED MOLECULAR LASER-AMPLIFIERS

A time- and space-dependent simulation for an optically pumped molecul ar laser amplifier has been carried out. The influence of superfluores cent emission, self-absorption of the laser emission and pump beam dep letion have been included. We have studied the effect of spatial overl ap of the pump and the signal beams and their intensity profile mismat ch on the amplifier extraction efficiency. Strong generation of superf luorescent emission is observed from that part of the excited amplifie r volume which is not probed by the input signal when the signal and t he pump beam do not overlap exactly. Thus, in order to achieve high am plifier extraction efficiency and a reduced level of superfluorescent emission, the pump and the signal beams should be overlapped spatially , and their intensity profiles matched. Also, the requirement of spati al overlap is more stringent for signal beams having uniform intensity profiles.