Calculation of harmonic generation during the multiphoton ionization of the hydrogen atom

The response of a hydrogen atom to an intense nonresonant laser field is investigated by direct numerical solution of the time-dependent Schrodinger equation. This calculation is nonperturbative and does not involve the eigenstates of the field-free atom. An ionization rate for three-photon ionization is calculated and found to be in excellent agreement with previous values. The time-dependent electric dipole moment is calculated; its Fourier transform yields the spectrum of scattered light. Odd-order harmonic peaks through at least the 25th order are present in the spectrum.