Controllable temporal twisting polarization within an ultrafast laser pulse

We propose a method for controlling the time-varying polarization of optical pulses by introducing a quarter-wave plate into a 4-f pulse shaper and using a spatial light modulator to impose a group delay. This setup enables the polarization state of the incident pulse to vary over time. Specifically, for linearly chirped incident pulses, the polarization ellipse twists uniformly over time, while its ellipticity changes monotonically. As the group delay increases, the pulse intensity gradually splits in the time domain, transitioning from a single pulse with uniformly twisting polarization to two circularly polarized pulses with opposite chirality. We provide a detailed and comprehensive explanation of this modulation process using analytical expressions.