2ND-HARMONIC GENERATION FROM A SURFACE OF AN ISOTROPIC GYROTROPIC MEDIUM IN THE CASE OF NORMAL INCIDENCE OF A GAUSSIAN PUMPING BEAM

Second harmonic generation from a surface is studied theoretically in the reflection and transmission geometries. The formulas obtained allo w polarization and amplitude characteristics of the field of a signal beam to be completely described at any point of its cross section. It is shown that the light intensity at the centers of both reflected and transmitted second harmonic beams is equal to zero, and the polarizat ion and the intensity vary over the beam cross section in a complicate d manner. A formula for the total power of the reflected signal is pre sented. The possibility for obtaining spectroscopic information on ten sors characterizing the quadratic nonlinearity of a medium and its sur face in the geometry of the problem considered is discussed, Modified boundary conditions for electromagnetic field that allow near-the-surf ace inhomogeneity and spatial dispersion of the optical response of a substance to be taken into account correctly in the model of a sharp b oundary were used in the calculations.