Tunable liquid crystal beam steering device based on Pancharatnam phase

Electro-optic (EO) beam steering offers several important advantages over traditional mechanical steering approaches for applications such as laser communication, LiDAR and autonomous vehicles. These advantages include a lower cost, faster steering rates, and a random access beam pointing capability. While progress towards replacing mechanical steering approaches has been promising, challenges remain to achieve large aperture sizes with tunable steering directions. In this paper, we propose a unique liquid crystal based Pancharatnam Phase Device (PPD) for beam steering. The PPD has the advantageous property of allowing a continuous and unbounded optical phase delay across an aperture without requiring any phase resets, thereby maximizing steering efficiency. Our PPD architecture employs a linear array of phase control elements (PCEs) to locally orient the liquid crystal director into a cycloidal pattern for beam steering. The PCEs are comprised of a fringe field switching (FFS) electrode structure to create an in-plane electric field with low-operating voltages and a fast liquid crystal response time of around several milliseconds. Detailed modeling of the proposed design will be presented which demonstrates the design concept.