Independent control over the amplitude,phase, and polarization of femtosecond pulses

We introduce a shaper setup which takes advantage of laser pulses passing through a spatial light modulator twice, thereby effectively utilizing a four-liquid crystal mask configuration. This approach grants control not only over the phase and polarization but also the amplitude. The Jones vector of the light wave after passing through the setup is considered in detail including polarization sensitive grating efficiency. A new method of counteracting the polarization dependent grating transmission is described and a comparison between the desired and recorded pulses is presented. PACS 42.25.Ja; 42.15.Eq; 42.65.Re