Method for spatial mode shifting in an actively frequency stabilized optical cavity for dual-color X-rays generation in BriXSinO

We report on the experimental proof of a technique for the implementation of dual-color X-ray generation via inverse Compton scattering in the BriXSinO project. Our technique is based on two identical optical cavities, with different interaction angles with the electron line. A fast (50 ms) shift of their fundamental modes allows an alternate Compton interaction, resulting in two alternate X-rays colors. As a proof of principle, we tested our technique on an experimental setup with the same geometry used for BriXSinO, demonstrating the feasibility of this method for a future implementation in a complete Compton source.