Coherence evolution of laser beams in cavities with variable-reflectivity mirrors

A theoretical analysis of the time evolution of spatial coherence in a large Fresnel-number laser cavity with use of the second-moment-analysis method and assuming quadratic (Gaussian) variable-reflectivity mirrors was found also to provide a satisfactory description of coherence growth inside a pulsed high-gain laser with use of either super-Gaussian or phase-unifying mirrors. The theoretical results are found to be in good agreement with the detailed experimental results from a high-gain, short-pulse Xe–Cl laser having a plane-parallel cavity equipped with both types of mirror.