Two-color free-electron laser with two orthogonal undulators

We discuss a two-color self-amplified spontaneous emission free-electron laser (FEL) amplifier where the emission is obtained from two orthogonally polarized undulators with different periods and field intensities. Nonaveraged and averaged equations are compared. The two radiations have not only different frequencies, but also different polarizations, while the total length of the device does not change with respect to usual single-color FELs. The wavelengths of two different colors can be changed by choosing different periods, while variation in the magnetic strengths can be used to modify the gain lengths. © Published by the American Physical Society.