Topic
Diffraction efficiency
About: Diffraction efficiency is a research topic. Over the lifetime, 10320 publications have been published within this topic receiving 158298 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: A diffraction efficiency of 60% with a polarization contrast ratio of >100:1 using a multilevel phase hologram made from two birefringent lithium niobate substrates and a single-layer SiO(2) thin-film antireflection coating on all surfaces can reduce reflections from the high-index substrates without significant effect on hologram performance.
Abstract: We constructed polarization-selective computer-generated holograms that apply an independent phase profile during readout by horizontal and vertical light polarizations. These elements are composed of two surface-relief-etched birefringent substrates joined face to face. We describe the design methodology for arbitrary birefringent substrate and gap materials. We show how these holograms are fabricated with standard microelectronics technology and discuss the effects of etching and alignment errors on performance. We demonstrated a diffraction efficiency of 60% with a polarization contrast ratio of >100:1 using a multilevel phase hologram made from two birefringent lithium niobate substrates. We also showed that a single-layer SiO(2) thin-film antireflection coating on all surfaces can reduce reflections from the high-index substrates without significant effect on hologram performance. We also consider some possible applications of this technology and demonstrate experimentally a dual focal-length lens and a self-interconnecting binary 2 × 2 polarization switch.
92 citations
TL;DR: In this paper, physical properties of polymer dispersed liquid crystal transmission gratings are investigated and analyzed with a sinusoidal dielectric tensor modulation model to determine the orientation and shape of nanometer-sized liquid crystal droplets in a polymer host.
Abstract: We investigate physical properties of polymer dispersed liquid crystal transmission gratings which influence the light diffraction efficiency behavior. Scanning electron microscopy is used to determine the orientation and shape of nanometer-sized liquid crystal droplets in a polymer host. Dependence of diffraction efficiency on light polarization suggests that the orientation of a liquid crystal within the ellipsoidal droplets is axial. The distribution of droplet orientations appears to vary for different grating spacings. The switching properties of the gratings are investigated and analyzed with a sinusoidal dielectric tensor modulation model. The analysis also takes into account orientational distribution of average directors and spatial distribution of the droplets. Temperature dependence of diffraction efficiency is tentatively explained by a structural transition within the droplets and the presence of impurities in droplets.
92 citations
TL;DR: In this paper, a two-region formulation of the rigorous electromagnetic boundary element method (BEM) is developed and applied to practical diffractive cylindrical lenses of continuous profile and with discrete levels (32, 8, and 2).
Abstract: A novel two-region formulation of the rigorous electromagnetic boundary element method (BEM) is developed and applied to practical diffractive cylindrical lenses of continuous profile and with discrete levels (32, 8, and 2). The performance of these diffractive lenses is presented for incident waves of TE and TM polarization, for a range of beam profiles, and for normal and nonnormal incidence. An optimum width of the Gaussian beam is determined. The BEM is shown to be accurate and versatile, providing the numerical and graphical results that are needed for analysis and design of diffractive elements.
92 citations
TL;DR: In this paper, the fixed holograms can be read out directly or after a positive-voltage pulse is applied that can dramatically enhance the diffraction efficiency, and single gratings as well as images are recorded and fixed.
Abstract: Photorefractive holograms stored in Sr0.75Ba0.25Nb2O6 crystals are electrically fixed at room temperature. The fixed holograms can be read out directly or after a positive-voltage pulse is applied that can dramatically enhance the diffraction efficiency. Single gratings as well as images are recorded and fixed.
91 citations
TL;DR: In this paper, a simple relation between the applied electric field and optical exposure is determined which allows electrical control of optically induced refractive index change, which can also be used to control diffraction efficiency of the holographic reconstruction process.
Abstract: Single‐crystal Sr0.75Ba0.25Nb2O6 when used in conjunction with an externally applied electric field is shown to be a sensitive volume holographic medium capable of high‐resolution information storage. Optically induced refractive index changes of 5 × 10−4 have been observed with laser exposure of 14 J/cm2. A simple relation between the applied electric field and optical exposure is determined which allows electrical control of optically induced refractive index change. In addition to control of the optically induced effect it is found that the applied electric field can also be used to control the diffraction efficiency of the holographic reconstruction process.
91 citations