PROPAGATION OF OPTICAL BEAMS IN ACTIVE MEDIA INSIDE GAUSSIAN CAVITIES

The evolution of relevant beam parameters of a light beam propagating through an iterated sequence of spherical lenses and Gaussian aperture s immersed in an active medium is investigated. This structure is a cl assical model for an optical resonator. The effective size of the fiel d distribution, the beam quality factor and the radius of wave front c urvature are calculated as functions of the number of transits. Steady -state values of these parameters are also determined and the dependen ce of the results on the gain of the medium, the aperture width and th e focal length is illustrated. A comparison with the case without acti ve medium is also discussed.