Photoelectric effect in the presence of a bichromatic laser field

Photoelectric effect in atomic hydrogen in the presence of bichromatic laser fields composed of a fundamental frequency and its second or third harmonics is investigated. The expression of the S-matrix for the laser-assisted photoelectric effect is derived in the length gauge, which can simplify the elements of the matrix. A general dressed wavefunction of the atom is derived in perturbation theory. The continuum state of the ejected electron is described by a Coulomb–Volkov wavefunction. Numerical results of photoionization cross section for the distinct second component are obtained and compared with the monochromatic field dressing case. It is shown that the photoionization cross section is modified notably by introducing the second component of field, especially when the colliding system absorbs or emits a considerable number of laser photons.