Optically switchable all-fiber optic polarization rotator

This study demonstrates an all-fiber optical polarization rotator and switch based on a side-polished fiber (SPF) overlaid with a photoresponsive liquid crystal (LC) containing a nematic LC and a photosensitive azobenzene molecule. The trans-cis photoisomerization of azobenzene modulates the overlaid LC's birefringence, changes the refractive index (RI) of the photoresponsive LC-overlaid SPF, and further controls and switches the phase retardation. This design achieves a 10° phase shift under switching time of less than 1 s. The demonstration has potential for an optically tunable in-line 2 × 2 fiber-optic switch or microstructured fiber-based photonic device controlled by the polarization of light.