Abstract
The effects of high-order fields of a tightly focused laser beam on the generation of relativistic nonlinear Thomson scattered radiations by a relativistic electron were investigated through numerical simulations. The high-order terms of the laser fields obtained by a series expansion in a diffraction angle were found to strongly affect the nonlinear Thomson scattered radiations by an increase in the transverse acceleration when electrons co-propagate with the laser pulse: the spectral range was broadened by a large factor and the angular power was enhanced by seven orders of magnitude compared to the corresponding values for a paraxial Gaussian laser beam. For electron energies higher than 200 MeV, the scaling exponent of the peak angular power with respect to the initial electron energy was also found to increase by a factor of 2.5 compared to the case of the paraxial laser beam.