The use of two different wavelength lasers in the nonlinear regime of the inverse Compton scattering interaction is proposed in order to provide a new strategy for controlling scattered photon energy distributions in the x-ray to $\gamma$-ray spectral region. In this nonlinear interaction, the component of the relativistic electron’s trajectory driven by a longer-wavelength laser with the normalized vector potential $a_{\mathrm{L}}\sim 1$ is a large oscillatory figure-8; in the proposed scenario a rapid small-amplitude oscillation induced by a shorter-wavelength laser is superimposed upon this figure-8. Thus, the electron’s momentum is mainly supplied from longer-wavelength laser, while the high-frequency part of the acceleration is given by shorter-wavelength laser. In this way, the harmonics radiated at high frequency from the oscillating electron can be strongly modified by the nonlinear motion initiated by the low frequency, large $a_{\mathrm{L}}$ laser resulting in the generation of the harmonics with the photon energy of $4{\gamma }^2\mathrm{h̵}({\omega }_{\mathrm{L},\mathrm{short}}+n{\omega }_{\mathrm{L},\mathrm{long}})$. In this paper, the electron’s kinetics in the two-wavelength laser field and the concomitant emitted radiation spectrum are examined, with numerical illustrations based on a classical Lienard-Wiechert potential formalism provided.

• Received 29 September 2011

DOI:https://doi.org/10.1103/PhysRevSTAB.14.120702

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Published by the American Physical Society