SPIE Optics and Photonics, Conference OP414, Advanced Wavefront Control: Methods, Devices, and Applications VI
Wide-angle, nonmechanical beam-steering using thin, liquid crystal polarization gratings
We introduce and demonstrate a compact, nonmechanical beamsteering device based on liquid crystal (LC) polarization gratings (PGs). Directional control of collimated light is essential for free-space optical communications, remote sensing, and related technologies. However, current beamsteering methods often require moving parts, or are limited to small angle operation, offer low optical throughput, and are constrained by size and weight. We employ multiple layers of anisotropic diffraction gratings (LCPGs) to achieve wide-angle (-40° to +40° field-of-regard), coarse beamsteering of 1550 nm light in a remarkably thin package. LCPGs are composed of bulk nematic LCs with a continuous periodic birefringence profile, can be made in switchable or polymer materials, and manifest distinctly compelling properties (experimentally realized): ~100% experimental diffraction efficiency into a single order, orthogonal circularly-polarized diffracted orders, and very low scattering. Light may be controlled within and between the zero- and first-diffraction orders by the handedness of the incident light and potentially by voltage applied to the PG itself. We implement a coarse steering device with several LCPGs matched with active halfwave LC variable retarders. Here, we present preliminary experimental results and discuss the unique capability of this wide-angle steering with breakthrough implications.
JK, COH, MJE, Lance Hosting, and Steve Serati (see http://www.bnonlinear.com/contact.php for contact)