OUTPUT CHARACTERISTICS OF AMPLIFIED-STIMULATED-EMISSION LASERS

The output characteristics of an amplified-stimulated-emission laser are developed with a simple model of a rod of lasing material along which the beam propagates in both directions. Detailed expressions are derived for the saturation of gain and spontaneous emission. From these a series of analytic models is developed for calculation of the output intensity and linewidth. The exact solution is obtained for the case in which the line has a rectangular profile, and this solution is used as the basis for a complete solution for inhomogeneous broadening and to validate an approximation used for the homogeneous case. The mixed case in which the line has both homogeneous and inhomogeneous components is developed. The role of collisional relaxation in changing the nature of broadening is discussed.