Reflective liquid crystal polarization gratings with high efficiency and small pitch

摘要

We report our experimental success in realizing high efficiency liquid crystal polarization gratings (LCPGs) on reflective substrates, with periods as small as 2.2μm, enabling the largest switchable LCPG diffraction angles reported yet for red light. Moreover, these gratings retain nearly ideal electro-optical properties, including > 95% hologram efficiency, high polarization contrast, sub-millisecond total switching times, and relatively low voltage operation (thresholds ～1.5V). We discuss two different fabrication approaches, each with its own set of advantages, which have resulted in gratings with the above compelling properties. We anticipate broad utility of these diffractive elements in a variety of applications.