Transverse profile effects on lasing without population inversion

We analyse the effects of a Gaussian transverse profile for the driving and laser fields on lasing without population inversion, in four different three-level schemes. We show that the lasing domains can be considerably reduced with respect to the plane-wave case in the V and in the cascade configuration driven in the upper transition, while in the ##IMG## [http://ej.iop.org/icons/common/Lambda.gif] {Lambda} and in the cascade configuration driven in the lower transition such domains are always larger in the Gaussian case.