Physical Review A
Coherent propagation and optical pumping in three-level systems
Bruce J. Herman, P. D. Drummond, Joseph H. Eberly, Božena Sobolewska
Abstract
We develop a theory to take into account the effects in coherent propagation of a small overlapping of the pump and probe pulses in a three-level system. The Maxwell equations reduce to coupled equations for variables which are related to the time-integrated field envelopes. We make comparisons of the propagation results to the Burnham-Chiao theory for a two-level amplifier and can predict when this theory breaks down. An application to superfluorescence is presented where a lengthening of the delay time is found. We treat Doppler broadening and find simplified equations in two cases: (a) a very broad line and (b) a very narrow line where the initial and final states are degenerate. For the broad-line case, with an appropriate choice of initial parameters, we can make the probe pulse approach any desired area for certain configurations of the levels.