Design of diffractive optical elementrs for mode shaping within custom laser resonators

Diffractive optical elements (DOEs) have been demonstrated that alter the fundamental mode of a laser resonator to a desired profile, notably by Leger et al.1,2 These, so-called mode-selecting elements (MSEs), usually operate within a Fabry-Pérot laser cavity by replacing one, or both, of the mirrors with a reflecting DOE. They have been mainly applied in solid-state laser systems, e.g., Nd:YAG. The advantages of these customised cavities include superior discrimination against higher-order modes,3 enabling single-mode operation and the inherently useful properties of the fundamental mode profiles that they can generate, e.g., flattops. These properties are much in demand for many applications including material processing.