Lossless generation of a single-lobe symmetric beam from the output of a CO2 waveguide laser array

The undesired side lobes in the far field emission of a linear array of phase coupled lasers can be reduced by using a phase correcting mirror outside the laser array cavity. Even in that case the beam has strong asymmetry acid astigmatism, that can be corrected by an off-axis spherical mirror, In this Letter we show the beam obtained experimentally with this kind of correction. The global optical set-up consists of three reflective optical elements producing a nearly lossless transformation of the field distribution from a periodic repetition of small highly divergent sources to a quasi-Gaussian symmetric beam.