F. Glotin et al., TEMPORAL STRUCTURE OF THE CLIO LASER MICROPULSES IN THE 2-COLOR REGIME, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 393(1-3), 1997, pp. 200-203
By using sum-frequency generation in a Michelson arrangement, we have
directly measured the temporal overlap between single-frequency microp
ulses in a two-color free-electron laser. As expected, the average sep
aration appears to be related to the slippage length between the elect
rons and light when passing through the undulator. The two colors are
then partly simultaneous, although there is not necessarily two-freque
ncy bunching in the electron beam.