Spectral Composition of Solid-State Laser Emission and Mode Discrimination by Various Cavity Elements

Abstract

The simplest solid-state laser embodies an active medium placed in a resonator cavity. In the earliest experiments on the generation of radiation in such lasers the cavity normally comprised two mirrors (metal or dielectric) deposited directly on the suitably finished (in the shape of spheres of definite radius or parallel planes) end faces of the active rod. It is understandable, then, that the first theoretical studies on the modal composition of the radiation in such a cavity [67–70] should presume the presence of only two mirrors. According to these studies the emission spectrum of the laser must consist of separate, equally spaced components, or modes (here and elsewhere we are concerned only with axial modes, i.e., TEM_00p modes in the classification of Fox and Li [67]), the distance between which (in cm^-1) is determined by the optical length of the cavity: δv_m = 1/2L.