We show how an interferometric setup containing a polarizing beam splitter and a slab of dispersive material allows control over the evolution of the instantaneous state of polarization of an optical pulse. With this proposed method the entire Poincar\'e sphere can be covered by varying the material's thickness. The ability to control the state of polarization over the duration of the pulse may be useful in a wide variety of applications.
Visser et al. (2026) studied this question.