SEMICLASSICAL THEORY OF STRONG-FIELD HARMONIC-GENERATION

The Schrodinger equation is integrated in space and time for calculation of the photoionization dynamics and harmonic generation in a generic one-dimensional model in a strong monochromatic field. These results are compared with classical results for the ionization and with semiclassical results for the harmonic generation, and generally good agreement is obtained. The semiclassical method introduced here for calculation of the harmonic generation consists of approximating the Heisenberg dipole moment operator by a classical trajectory and then averaging over an ensemble of such trajectories by means of the initial wave function. This average represents a semiclassical approximation to the temporally oscillating, field-induced dipole moment, which is used to calculate the photoemission spectrum.