GRADED-PHASE MIRROR RESONATOR WITH A SUPER-GAUSSIAN OUTPUT IN A CW-CO2 LASER

Two graded-phase mirror (GPM) resonators have been designed to produce super-Gaussian output beam profiles of order 4 and 6. An inverse prop agation method was used to calculate the appropriate shape of the GPM' s. Previous experimental work with a pulsed TEA-CO2 laser has already confirmed the high transverse mode discrimination offered by such cust om resonators, as anticipated by a theoretical analysis of their diffr actional properties. Here, we extend these results by presenting new e xperimental measurements with a CW-CO2 laser. The main objective of th is paper is to demonstrate the super-Gaussian beam shape produced by t hese custom resonators. This is assessed with numerical simulations in volving the incoherent superposition of transverses modes. The experim ental results obtained with the GPM resonators, including measurements of the propagation of the output beam profile, are compared to those of a conventional semiconfocal cavity, and show higher monomode power extraction.