2ND-HARMONIC GENERATION BY REFLECTION OF A 2-DIMENSIONAL LASER-BEAM FROM THE SURFACE OF A CHIRAL MEDIUM

Second harmonic generation (SHG) by reflection of a two-dimensional el liptically polarized Gaussian beam (the field of which is homogeneous in the direction perpendicular to the plane of incidence) from the sur face of an isotropic gyrotropic medium is theoretically investigated. The modified boundary conditions for the electromagnetic field includi ng the surface density of current of bound charges are used for taking correct account of the near-surface inhomogeneity and the spatial dis persion of the optical response of the medium. The formulas obtained f or the electric field of the reflected beam with the doubled frequency show that this beam has a non-Gaussian transverse profile. In contras t to the case of the plane wave pumping, the SHG signal is present eve n for the normal incidence of the pumping beam.