Diffraction efficiency

About: Diffraction efficiency is a research topic. Over the lifetime, 10320 publications have been published within this topic receiving 158298 citations.

Fixing method for narrow bandwidth volume holograms in photorefractive materials

Abstract: An improved method for storing permanent holographic gratings in photorefractive materials for use in narrow band filters such as the H60 filter, as well as the filters themselves. The invention also provides an improved method of controlling the electric field and the nature of the photorefraction to minimize wavelength shifts and band broadening at a minimal reduction of diffraction efficiency.

Uniform theory of the Talbot effect with partially coherent light illumination

Abstract: A uniform formulation for the self-imaging of gratings with any kind of partially coherent illumination is developed in terms of the cross mutual spectral density of the partial coherence theory. The formulation includes the time diffractive intensity distribution and the averaged diffractive intensity distribution at self-imaging distances and can be applied to both continuous and temporal illuminations with any kind of spectra. It is found that the averaged intensity distribution is related only to the intensity spectrum of illumination. The continuous polychromatic illumination and the ultrashort laser pulses with or without frequency chirp are then studied by a numerical stimulation. It is shown that the ultrashort laser pulse and the continuous polychromatic illuminations have similar averaged self-image distributions. Thus the Talbot effect may help in the study of the temporal and spectral characteristics of ultrashort laser pulses. An experiment with an LED is given, as well.

Electron diffraction from free-standing, metal-coated transmission gratings

Abstract: Electron diffraction from a free-standing nanofabricated transmission grating was demonstrated, with energies ranging from 125 eV to 25 keV. Observation of 21 diffraction orders highlights the quality of the gratings. The image charge potential due to one electron was measured by rotating the grating. These gratings may pave the way to low-energy electron interferometry.

Holographic diffraction gratings with enhanced sensitivity based on epoxy-resin photopolymers

Abstract: Photopolymers are interesting materials to obtain high-quality performance for the volume holographic data storage with a low noise and high diffraction efficiency. In this paper, the recording of holographic diffraction gratings with a spatial frequency of approximately 1940lines/mm in photopolymerizable epoxy resin materials is experimentally demonstrated. Diffraction efficiency near 92% and an energetic sensitivity of 11.7×10-3cm2/J are achieved by designing the proper structure of matrix and also optimizing photopolymer compositions. The effect of photopolymer compositions on the fundamental optical properties is also discussed.

Resonant grating polarizers made with silicon nitride, titanium dioxide, and silicon: Design, fabrication, and characterization

Abstract: We present the design, fabrication, and characterization of guided-mode resonance (GMR) linear polarizers that operate in the optical communications C-band near a wavelength of 1550 nm. We provide theoretical and experimental spectra using resonant elements fashioned in three material systems. In particular, we investigate silicon nitride resonant gratings and titanium dioxide gratings on glass substrates as well as silicon-on-quartz gratings. These materials exhibit very low losses and are capable of high diffraction efficiencies and extinction ratios; thus, high-power laser applications may be enabled. We present the methods applied to fabricate these GMR devices as well as means to ascertain their fabricated physical parameters. We quantify increased polarizer bandwidth with increased grating refractive-index modulation. The numerical results obtained with the fabricated-device parameters agree well with the experimental measured spectra.