Phase dependence of Thomson scattering in an ultraintense laser field

The Thomson scattering spectra of an electron by an ultraintense laser field are computed. It is found that the electron orbit, and therefore its nonlinear Thomson scattering spectra, depend critically on the amplitude of the ultraintense laser field and on the phase at which the electron sees the laser electric field. Contrary to some customary notions, the Thomson scattering spectra, in general, do not occur at integer multiples of the laser frequency and the maximum frequency is proportional to the first instead of the third power of the electric field strength for the case of an ultraintense laser. The implications of these findings are discussed. See the same authors\u27 “Erratum: Phase dependence of Thomson scattering in an ultraintense laser field (Physics Plasmas (2002) 9 (4325)),” Physics of Plasmas 10:1, p. 327 (Jan 2003)