TY - CPAPER
AU - Prince, K.C.
TI - Measurements and Future Prospects for Coherent Control with FEL Radiation
J2 - Proc. of FEL2015
AB - FELs produce ultrafast, intense, polarised and coherent pulses of light, similar to optical lasers, and these properties have been exploited in FEL experiments, with one exception, namely longitudinal coherence. There have been few if any FEL applications of this property. The FERMI FEL is longitudinally coherent, and can be configured to produce simultaneous, different wavelengths which are mutually coherent, with a well-defined phase relationship. We have exploited this in recent experiments to produce overlapping pulses of first and second harmonic light with a tunable phase delay, and perform an experiment on neon atoms. The first harmonic was set to about 63 nm and high intensity, and the second harmonic to lower intensity and half of this wavelength. The first harmonic gave rise to two-photon photoemission, while the second harmonic caused single photon emission. At appropriate relative intensities of the two beams, the emitted photoelectrons interfered to give asymmetric angular distributions (Brumer-Shapiro type experiment.) The asymmetry depended on the value of the phase difference between the two wavelengths, thus demonstrating their correlation in phase. The relative phase was controlled with a precision of 3 attoseconds. This result opens the way to coherent control experiments in the short wavelength region, and some planned applications will be illustrated.
PB - JACoW
CY - Geneva, Switzerland
ER -