Abstract

The study of nonlinear optical processes in an isotropic medium that are forbidden according to symmetry properties of medium attracts considerable interest in recent years. One of these processes is second harmonic generation in isotropic medium that is forbidden in the electric-dipole approximation. Several symmetry-breaking mechanisms have been proposed to explain the experimental results. We show that second harmonic generation could arise from the spatially nonlocal interactions, because in spatially inhomogeneous field the atomic wave function could be significantly distorted.

© 2000 IEEE