High-efficiency, tunable, fringe-field switching-mode beam steering based on a liquid crystal Pancharatnam phase.

We have fabricated, characterized, and analyzed a recently proposed non-mechanical beam steering device based on the Pancharatnam-Berry phase in a liquid crystal. The architecture of our proposed device employs a linear array of phase control elements (PCEs) to locally control the orientation of the liquid crystal director into a cycloidal pattern to deflect transmitted light. The PCEs are comprised of a fringe-field switching electrode structure that can provide a variable in-plane electric field. Detailed optimization of the director configuration is in a good agreement with experimental results showing that the half-wave retardation condition has been uniformly achieved across the aperture. Moreover, efficiency simulations using a finite-difference time-domain algorithm verify a high beam steering efficiency for the proposed device.

Design of a large aperture, tunable, Pancharatnam phase beam steering device.

Replacing mechanical optical beam steering devices with non-mechanical electro-optic devices has been a long-standing desire for applications such as space-based communication, LiDAR and autonomous vehicles. While promising progress has been achieved to non-mechanically deflect light with high efficiency over a wide angular range, significant limitations remain towards achieving large aperture beam steering with a tunable steering direction. In this paper, we propose a unique liquid crystal based Pancharatnam Phase Device for beam steering which can provide both tunability and a fast response times in a format scalable to large apertures. This architecture employs a linear array of phase control elements to locally control the orientation of the liquid crystal director into a cycloidal pattern to deflect transmitted light. The PCEs are comprised of a fringe field switching electrode structure that can provide a variable in-plane electric field. Detailed modeling of the proposed design is presented which demonstrates that such a device can achieve a high degree of uniformity as it rotates the LC molecules over the 180 ° angular range required to create a Pancharatnam phase device.

"Achromatic limits" of Pancharatnam phase lenses.

Lenses based on the Pancharatnam phase have the advantage of being thin and inexpensive. Unfortunately, their optical effect is strongly wavelength dependent, and their applications generally are limited by the requirement of a monochromatic source. However, low-power lenses based on the Pancharatnam phase can be considered for applications over the visible range. In this paper, we provide intuitive "limits" for the lens power, below which these devices can be considered for use with the eye and visible light imaging applications.