Generation of arbitrary complex quasi-non-diffracting optical patterns

摘要

Due to their unique ability to maintain an intensity distribution uponpropagation, non-diffracting light fields are used extensively in various areasof science, including optical tweezers, nonlinear optics and quantum optics, inapplications where complex transverse field distributions are required.However, the number and type of rigorously non-diffracting beams is severelylimited because their symmetry is dictated by one of the coordinate systemwhere the Helmholtz equation governing beam propagation is separable. Here, wedemonstrate a powerful technique that allows the generation of a rich varietyof quasi-non-diffracting optical beams featuring nearly arbitrary intensitydistributions in the transverse plane. These can be readily engineered viamodifications of the angular spectrum of the beam in order to meet therequirements of particular applications. Such beams are not rigorouslynon-diffracting but they maintain their shape over large distances, which maybe tuned by varying the width of the angular spectrum. We report the generationof unique spiral patterns and patterns involving arbitrary combinations oftruncated harmonic, Bessel, Mathieu, or parabolic beams occupying differentspatial domains. Optical trapping experiments illustrate the opto-mechanicalproperties of such beams.