Hz. Zhang et Jy. Gao, EFFECTS OF TRANSVERSE PROFILE OF PROBE AND DRIVING FIELDS ON THE GAININ A RAMAN-DRIVEN 4-LEVEL SYSTEM, Physical review. A, 56(3), 1997, pp. 2225-2232
In this paper the effects of the transverse profile of the probe and d
riving fields on the gain in a Raman-driven four-level system are disc
ussed. The results show that when transverse effects are included, the
probe gain spectrum has a different structure compared with that in t
he plane-wave approximation, the optimum focal position of a focus len
s for the maximum gain is not at the center of the sample cell, and th
e gain is very sensitive to the changes of focal position when the wai
st of the driving field is small.