Production and properties of two-color radiation generated by using a Free-Electron Laser with two orthogonal undulators

We present the analysis of the two-color Self Amplified Spontaneous Emission generated by a Free-Electron Laser amplifier constituted by two orthogonally polarized undulators with different periods and field intensities. Equations deduced in a non-averaged and in an averaged model have been integrated and compared. The two pulses have different frequencies, ruled by proper resonance conditions, and different polarizations, while the total length of the device does not change noticeably with respect to usual single color FELs. The wavelengths of two colors can be changed by choosing different periods, while variation in the magnetic strengths can be used to modify the gain lengths in view of various applications