With the use of spatial light modulators it became possible to implement in experiments the method of controlling the space-time intensity distribution of femtosecond laser pulses stretched to picosecond duration. Cylindrical and quasi-ellipsoidal intensity distributions were obtained and characterized by means of a 2D spectrograph and a cross-correlator.

No abstract

A method for shaping photocathode laser driver pulses into 3D ellipsoidal form has been proposed and implemented. The key idea of the method is to use a chirped Bragg grating recorded within the ellipsoid volume and absent outside it. If a beam with constant (within the grating reflection band) spectral density and uniform (within the grating aperture) cross-section is incident on such a grating, the reflected beam will be a 3D ellipsoid in space and time. 3D ellipsoidal beams were obtained in experiment for the first time. It is expected that such laser beams will allow reducing the electron bunch emittance when applied at R ± photo injectors.

No abstract

The specific features of experimental implementation of a cross-correlator with a scan rate above 1600 cm s-1 and a spatial delay amplitude of more than 15 mm are considered. The possibility of measuring the width of femtosecond pulses propagating in a train 300 ms in duration with a repetition rate of 1 MHz is demonstrated. A time resolution of 300 fs for the maximum time window of 50 ps is attained. The cross-correlator is aimed at testing 3D pulses of a laser driver of an electron photo-injector.