Interferometric beam shaping

Abstract

Many commercial laser systems deliver a beam having a Gaussian intensity profile, however, numerous applications require other intensity profiles (top-hat, hollow beam, Bessel beam,…) which are in general obtained by converting the standard Gaussian beam (GB) through transparent diffractive optical elements (DOE). Laser beam shaping (LBS) by use of DOE's is a topic that has been intensively developed over a long time whether the DOE is programmable or unprogrammable. Although, DOE's are a great help to many LBS problems they have an inherent drawback which is a relatively high cost. Recently, we have experimentally demonstrated the LBS ability resulting from the coaxial superposition of two CW coherent Gaussian beams. This technique is classified under interferometric LBS techniques contrasting with the usual ones based on diffraction. In particular, we demonstrate the reshaping of a Gaussian beam into a bottle beam or flat-top beam in the focal plane of a focusing lens.