@article{kim_li_miskiewicz_oh_kudenov_escuti_2015, title={Fabrication of ideal geometric-phase holograms with arbitrary wavefronts}, volume={2}, ISSN={["2334-2536"]}, DOI={10.1364/optica.2.000958}, abstractNote={Throughout optics and photonics, phase is normally controlled via an optical path difference. Although much less common, an alternative means for phase control exists: a geometric phase (GP) shift occurring when a light wave is transformed through one parameter space, e.g., polarization, in such a way as to create a change in a second parameter, e.g., phase. In thin films and surfaces where only the GP varies spatially—which may be called GP holograms (GPHs)—the phase profile of nearly any (physical or virtual) object can in principle be embodied as an inhomogeneous anisotropy manifesting exceptional diffraction and polarization behavior. Pure GP elements have had poor efficiency and utility up to now, except in isolated cases, due to the lack of fabrication techniques producing elements with an arbitrary spatially varying GP shift at visible and near-infrared wavelengths. Here, we describe two methods to create high-fidelity GPHs, one interferometric and another direct-write, capable of recording the wavefront of nearly any physical or virtual object. We employ photoaligned liquid crystals to record the patterns as an inhomogeneous optical axis profile in thin films with a few μm thickness. We report on eight representative examples, including a GP lens with F/2.3 (at 633 nm) and 99% diffraction efficiency across visible wavelengths, and several GP vortex phase plates with excellent modal purity and remarkably small central defect size (e.g., 0.7 and 7 μm for topological charges of 1 and 8, respectively). We also report on a GP Fourier hologram, a fan-out grid with dozens of far-field spots, and an elaborate phase profile, which showed excellent fidelity and very low leakage wave transmittance and haze. Together, these techniques are the first practical bases for arbitrary GPHs with essentially no loss, high phase gradients (∼rad/μm), novel polarization functionality, and broadband behavior.}, number={11}, journal={OPTICA}, author={Kim, Jihwan and Li, Yanming and Miskiewicz, Matthew N. and Oh, Chulwoo and Kudenov, Michael W. and Escuti, Michael J.}, year={2015}, month={Nov}, pages={958–964} }
 @article{lehmuskero_li_johansson_kall_2014, title={Plasmonic particles set into fast orbital motion by an optical vortex beam}, volume={22}, number={4}, journal={Optics Express}, author={Lehmuskero, A. and Li, Y. M. and Johansson, P. and Kall, M.}, year={2014}, pages={4349–4356} }
 @article{li_dudley_mhlanga_escuti_forbes_2013, title={Generating and analyzing non-diffracting vector vortex beams}, volume={8843}, ISSN={["1996-756X"]}, DOI={10.1117/12.2027249}, abstractNote={We experimentally generate non-diffracting vector vortex beams by using a Spatial Light Modulator (SLM) and an azimuthal birefringent plate (q-plate). The SLM generates scalar Bessel beams and the q-plate converts them to vector vortex beams. Both single order Bessel beam and superposition cases are studied. The polarization and the azimuthal modes of the generated beams are analyzed. The results of modal decompositions on polarization components are in good agreement with theory. We demonstrate that the generated beams have cylindrical polarization and carry polarization dependent Orbital Angular Momentum (OAM).}, journal={LASER BEAM SHAPING XIV}, author={Li, Yanming and Dudley, Angela and Mhlanga, Thandeka and Escuti, Michael J. and Forbes, Andrew}, year={2013} }
 @article{dudley_li_mhlanga_escuti_forbes_2013, title={Generating and measuring nondiffracting vector Bessel beams}, volume={38}, ISSN={["1539-4794"]}, DOI={10.1364/ol.38.003429}, abstractNote={Nondiffracting vector Bessel beams are of considerable interest due to their nondiffracting nature and unique high-numerical-aperture focusing properties. Here we demonstrate their creation by a simple procedure requiring only a spatial light modulator and an azimuthally varying birefringent plate, known as a q-plate. We extend our control of both the geometric and dynamic phases to perform a polarization and modal decomposition on the vector field. We study both single-charged Bessel beams as well as superpositions and find good agreement with theory. Since we are able to encode nondiffracting modes with circular polarizations possessing different orbital angular momenta, we suggest these modes will be of interest in optical trapping, microscopy, and optical communication.}, number={17}, journal={OPTICS LETTERS}, author={Dudley, Angela and Li, Yanming and Mhlanga, Thandeka and Escuti, Michael and Forbes, Andrew}, year={2013}, month={Sep}, pages={3429–3432} }
 @article{miskiewicz_kim_li_komanduri_escuti_2012, title={Progress on large-area polarization grating fabrication}, volume={8395}, ISSN={["0277-786X"]}, DOI={10.1117/12.921572}, abstractNote={Over the last several years, we have pioneered liquid crystal polarization gratings (PGs), in both switchable and polymer versions. We have also introduced their use in many applications, including mechanical/non-mechanical laser beam steering and polarization imaging/sensing. Until now, conventional holographic congurations were used to create PGs where the diameter of the active area was limited to 1-2 inches. In this paper, we discuss a new holography setup to fabricate large area PGs using spherical waves as the diverging coherent beams. Various design parameters of this setup are examined for impact on the quality of the recorded PG profile. Using this setup, we demonstrate a large area polymer PG with approximately 66 inch square area, and present detailed characterization.}, journal={ACQUISITION, TRACKING, POINTING, AND LASER SYSTEMS TECHNOLOGIES XXVI}, author={Miskiewicz, Matthew N. and Kim, Jihwan and Li, Yanming and Komanduri, Ravi K. and Escuti, Michael J.}, year={2012} }