Study of squeezed state on free electron lasers

Preliminary investigations on squeezed state of FEL have been undertaken at the Duke FEL lab by means of photon counting experiments. We report photon statistics for spontaneous undulator radiation from Duke Storage Ring. Photon counting measurements have also been constructed on the Mark III FEL to obtain the statistical behavior of the visible harmonics of the infrared radiation. The initial experimental data demonstrate that the squeezing of optical phase fluctuations in an FEL is directly associated with the phase regulation of the electron beam as a result of FEL bunching. Simulation results on phase fluctuations in FEL radiation are also presented which support the above viewpoint. Further measurements are in process in an attempt to obtain better understanding on the effect of quantum fluctuations on the FEL interaction.