Continuous large-angle beam steering using in-plane shifting of two Pancharatnam-Berry phase liquid crystal lenses

Liquid crystal based non-mechanical beam steering devices have been widely used for manipulating light. However, their deflection angle is often discrete and limited. To achieve continuous two-dimensional and large deflection angles simultaneously, a new device using two cascaded Pancharatnam-Berry phase lenses (PBLs) with in-plane shifting is proposed. From our analysis, the combined phase pattern of these two cascaded PBLs behaves as a beam deflector. In the experiment, we fabricated two PBLs with multi-twist structures and demonstrated continuous changeable deflection angles. Very good agreement between experiment and simulation is obtained. The maximum deflection angle of such a beam steerer reaches ±35.3°, ±29.7°, and ±24.7°at λ=633 nm, 532 nm, and 457 nm, which corresponds to f/1.5, f/1.8, and f/2.1 for the PBL, respectively.