Miniaturized Optical Polarization Rotator on a Microfiber Loop Using Berry’s Phase

Control of optical polarization plays a key role in various fields of optical science and engineering. Light propagating along an out-of-plane path acquires a Berry's phase, which rotates the polarization of the incident light. Herein, a miniaturized optical polarization rotator based on a microfiber loop is proposed and demonstrated with large polarization deflection angle (-85 degrees) with low insertion loss (-1 dB). It operates over a wide bandwidth from 1400 nm to 1650 nm, because the Berry's phase only depends on the optical path. Moreover, the influence of geometric structures on the performance of the microfiber-loop device, including mode cross-talk, birefringence and working bandwidth, are systematically explored. This work provides an alternative scheme to realize optical microfiber polarization rotators, which can be readily used in optical fiber sensors and polarimetric interferometry.