Abstract In this review paper,we report recent progress on Pancharatnam-Berry (PB) phase optical elements, such as lens, grating, and deflector. PB lenses exhibit a fast switching time between two or more focal lengths with large diopter change and aperture size, which is particularly attractive for addressing the accommodation mismatch in head-mounted display devices. On the other hand, PB gratings and deflectors offer a large-angle beam deflection with wide acceptance cone and high efficiency, as compared to conventional volume gratings. Such merits provide great advantages for waveguide-coupling augmented reality headsets. Moreover, the thickness of PB optical elements is only a few micrometers, thus they can be conveniently integrated into modern wearable display systems.

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Recent progress in Pancharatnam–Berry phase optical elements and the applications for virtual/augmented realities

Liquid-crystal-based Pancharatnam–Berry phase optical elements (PBOEs), also known as diffractive wave plates (DWPs), geometric phase optics (GPO), or geometric phase holograms (GPHs), are functional planar structures with patterned orientation of anisotropy axis. Several scientifically interesting yet practically useful electro-optical effects, such as focusing, beam splitting, waveguide coupling, and wavelength filtering, have been realized with PBOEs. Because of the high degree of optical tunability, polarization selectivity, nearly 100% diffraction efficiency, and simple fabrication process, PBOEs have found widespread applications in emerging display systems, particularly virtual/augmented/mixed reality displays and head-up displays. In this review, we will describe the basic operation principles, present device fabrication procedures, discuss numerical modeling methods, and address applications of PBOEs in emerging display systems.

Pancharatnam–Berry optical elements for head-up and near-eye displays [Invited]

Planar and ultrathin liquid crystal (LC) polarization optical elements have found promising applications in augmented reality (AR), virtual reality (VR), and photonic devices. In this paper, we give a comprehensive review on the operation principles, device fabrication, and performance of these optical elements. Optical simulations methods for optimizing the device performance are discussed in detail. Finally, some potential applications of these devices in AR and VR systems are illustrated and analyzed.

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Planar liquid crystal polarization optics for augmented reality and virtual reality: from fundamentals to applications

Planar optical elements that can manipulate the multidimensional physical parameters of light efficiently and compactly are highly sought after in modern optics and nanophotonics. In recent years, the geometric phase, induced by the photonic spin-orbit interaction, has attracted extensive attention for planar optics due to its powerful beam shaping capability. The geometric phase can usually be generated via inhomogeneous anisotropic materials, among which liquid crystals (LCs) have been a focus. Their pronounced optical properties and controllable and stimuli-responsive self-assembly behavior introduce new possibilities for LCs beyond traditional panel displays. Recent advances in LC-mediated geometric phase planar optics are briefly reviewed. First, several recently developed photopatterning techniques are presented, enabling the accurate fabrication of complicated LC microstructures. Subsequently, nematic LC-based transmissive planar optical elements and chiral LC-based broadband reflective elements are reviewed systematically. Versatile functionalities are revealed, from conventional beam steering and focusing, to advanced structuring. Combining the geometric phase with structured LC materials offers a satisfactory platform for planar optics with desired functionalities and drastically extends exceptional applications of ordered soft matter. Some prospects on this rapidly advancing field are also provided.

Liquid-Crystal-Mediated Geometric Phase: From Transmissive to Broadband Reflective Planar Optics

The objective of the present invention is providing optical systems for controlling with propagation of light beams in lateral and angular space, and through optical apertures. Said light beams include laser beams as well as beams with wide spectrum of wavelengths and large divergence angles. Said optical systems are based on combination of diffractive waveplates with diffractive properties that can be controlled with the aid of external stimuli such as electrical fields, temperature, optical beams and mechanical means.

Broadband optics for manipulating light beams and images

Geometrical phase or the fourth generation (4G) optics enables realization of optical components (lenses, prisms, gratings, spiral phase plates, etc.) by patterning the optical axis orientation in the plane of thin anisotropic films. Such components exhibit near 100% diffraction efficiency over a broadband of wavelengths. The films are obtained by coating liquid crystalline (LC) materials over substrates with patterned alignment conditions. Photo-anisotropic materials are used for producing desired alignment conditions at the substrate surface. We present and discuss here an opportunity of producing the widest variety of "free-form" 4G optical components with arbitrary spatial patterns of the optical anisotropy axis orientation with the aid of a digital spatial light polarization converter (DSLPC). The DSLPC is based on a reflective, high resolution spatial light modulator (SLM) combined with an "ad hoc" optical setup. The most attractive feature of the use of a DSLPC for photoalignment of nanometer thin photo-anisotropic coatings is that the orientation of the alignment layer, and therefore of the fabricated LC or LC polymer (LCP) components can be specified on a pixel-by-pixel basis with high spatial resolution. By varying the optical magnification or de-magnification the spatial resolution of the photoaligned layer can be adjusted to an optimum for each application. With a simple "click" it is possible to record different optical components as well as arbitrary patterns ranging from lenses to invisible labels and other transparent labels that reveal different images depending on the side from which they are viewed.

Digital polarization holography advancing geometrical phase optics.

The present invention relates to methods and apparatus for providing a variable optic insert into an ophthalmic lens. The variable optic insert may have surfaces within that have differing radii of curvature. A liquid crystal layer may be used to provide a variable optic function and in some embodiments, the liquid crystal layer may comprise polymer networked regions of interstitially located liquid crystal material. An energy source is capable of powering the variable optic insert included within the ophthalmic lens. In some embodiments, an ophthalmic lens is cast-molded from a silicone hydrogel. The various ophthalmic lens entities may include electroactive liquid crystal layers to electrically control refractive characteristics.

Method and apparatus for ophthalmic devices comprising dielectrics and liquid crystal polymer networks

Method and apparatus for ophthalmic devices including shaped liquid crystal polymer networked regions of liquid crystal

This invention discloses methods and apparatus for providing a variable optic insert into an ophthalmic lens. A liquid crystal layer may be used to provide a variable optic function and in some examples, an alignment layer for the liquid crystal layer may be patterned in a cycloidally dependent manner. The patterning may allow for a polarization dependent lens in some examples. An energy source is capable of powering the variable optic insert included within the ophthalmic lens. In some examples, an ophthalmic lens is cast-molded from a silicone hydrogel. The various ophthalmic lens entities may include electroactive liquid crystal layers to electrically control optical characteristics.

Methods and apparatus for ophthalmic devices including cycloidally oriented liquid crystal layers

This invention discloses methods and apparatus for providing an ophthalmic lens of variable optical power. The variable optic insert may have surfaces within that have differing radii of curvature. The variable optic insert may also comprise polarizing elements. In some embodiments, the variable optic insert may affect polarization components of light differently and enable a bifocal type ophthalmic device. An energy source is capable of powering the variable optic insert included within the ophthalmic lens. In some embodiments, an ophthalmic lens is cast-molded from a silicone hydrogel. The various ophthalmic lens entities may include electroactive liquid crystal layers to electrically control refractive characteristics.

Olena Uskova

Papers

Digital polarization holography advancing geometrical phase optics.

Method and apparatus for ophthalmic devices comprising dielectrics and liquid crystal polymer networks

Method and apparatus for ophthalmic devices including shaped liquid crystal polymer networked regions of liquid crystal

Methods and apparatus for ophthalmic devices including cycloidally oriented liquid crystal layers

Variable optic ophthalmic device including shaped liquid crystal elements and polarizing elements