 Laser linewidth from high-power high-gain pulsed laser oscillators, comprising line narrowing optics, is a function of the geometrical and dispersive features of the laser cavity.To a first approximation the laser linewidth, in an optimized cavity, is directly proportional to the beam divergence of the emission multiplied by the inverse of the "overall intracavity dispersion".That is, 

This is known as the "cavity linewidth equation" where formula_104 is the beam divergence and the term in parenthesis (elevated to –1) is the overall intracavity dispersion.