@article{komanduri_lawler_escuti_2013, title={Multi-twist retarders: broadband retardation control using self-aligning reactive liquid crystal layers}, volume={21}, ISSN={["1094-4087"]}, DOI={10.1364/oe.21.000404}, abstractNote={We report on a family of complex birefringent elements, called Multi-Twist Retarders (MTRs), which offer remarkably effective control of broadband polarization transformation. MTRs consist of two or more twisted liquid crystal (LC) layers on a single substrate and with a single alignment layer. Importantly, subsequent LC layers are aligned directly by prior layers, allowing simple fabrication, achieving automatic layer registration, and resulting in a monolithic film with a continuously varying optic axis. In this work, we employ a numerical design method and focus on achromatic quarter- and half-wave MTRs. In just two or three layers, these have bandwidths and general behavior that matches or exceeds all traditional approaches using multiple homogenous retarders. We validate the concept by fabricating several quarter-wave retarders using a commercial polymerizeable LC, and show excellent achromaticity across bandwidths of 450-650 nm and 400-800 nm. Due to their simple fabrication and many degrees of freedom, MTRs are especially well suited for patterned achromatic retarders, and can easily achieve large bandwidth and/or low-variation of retardation within visible through infrared wavelengths.}, number={1}, journal={OPTICS EXPRESS}, author={Komanduri, Ravi K. and Lawler, Kristopher F. and Escuti, Michael J.}, year={2013}, month={Jan}, pages={404–420} }
 @article{kim_komanduri_lawler_kekas_escuti_2012, title={Efficient and monolithic polarization conversion system based on a polarization grating}, volume={51}, ISSN={["2155-3165"]}, DOI={10.1364/ao.51.004852}, abstractNote={We introduce a new polarization conversion system (PCS) based on a liquid-crystal polarization grating (PG) and louvered wave plate. A simple arrangement of these elements laminated between two microlens arrays results in a compact and monolithic element, with the ability to nearly completely convert unpolarized input into linearly polarized output across most of the visible bandwidth. In our first prototypes, this PG-PCS approach manifests nearly 90% conversion efficiency of unpolarized to polarized for ±11° input light divergence, leading to an energy efficient picoprojector that presents high efficacy (12 lm/W) with good color uniformity.}, number={20}, journal={APPLIED OPTICS}, author={Kim, Jihwan and Komanduri, Ravi K. and Lawler, Kristopher F. and Kekas, D. Jason and Escuti, Michael J.}, year={2012}, month={Jul}, pages={4852–4857} }
 @article{komanduri_kim_lawler_escuti_2012, title={Multi-twist retarders for broadband polarization transformation}, volume={8279}, ISSN={["0277-786X"]}, DOI={10.1117/12.913795}, abstractNote={We introduce a family of broadband retarders, comprised of a low number of twisted nematic liquid crystal layers, that accomplishes well-controlled polarization transformation for nearly any bandwidth desired. For example, we show that broadband linear to circular polarization conversion can be achieved with only two twist layers where the performance matches the popular three-waveplate approach by Pancharatnam. Using liquid crystal polymers on a single substrate, we show how these multi-twist retarders are embodied as a monolithic birefringent plate with excellent performance and potentially very low cost.}, journal={EMERGING LIQUID CRYSTAL TECHNOLOGIES VII}, author={Komanduri, Ravi K. and Kim, Jihwan and Lawler, Kristopher F. and Escuti, Michael J.}, year={2012} }
 @article{komanduri_lawler_escuti_2011, title={A High Throughput Liquid Crystal Light Shutter for Unpolarized Light using Polymer Polarization Gratings}, volume={8052}, ISSN={["0277-786X"]}, DOI={10.1117/12.887140}, abstractNote={We report on a broadband, diffractive, light shutter with the ability to modulate unpolarized light. This polarizer-free approach employs a conventional liquid crystal (LC) switch, combined with broadband Polarization Gratings (PGs) formed with polymer LC materials. The thin-film PGs act as diffractive polarizing beam-splitters, while the LC switch operates on both orthogonal polarization states simultaneously. As an initial experimental proof-of- concept for unpolarized light with ±7° aperture, we utilize a commercial twisted-nematic LC switch and our own polymer PGs to achieve a peak transmittance of 80% and peak contrast ratio of 230:1. We characterize the optoelectronic performance, discuss the limitations, and evaluate its use in potential nonmechanical shutter applications (imaging and non-imaging).}, journal={ACQUISITION, TRACKING, POINTING, AND LASER SYSTEMS TECHNOLOGIES XXV}, author={Komanduri, Ravi K. and Lawler, Kris F. and Escuti, Michael J.}, year={2011} }