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Diffraction grating
About: Diffraction grating is a research topic. Over the lifetime, 24884 publications have been published within this topic receiving 372437 citations. The topic is also known as: grating.
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TL;DR: In this paper, the problem of diffraction by a perfectly conducting lamellar grating is examined numerically and analytically by use of a modal expansion technique and the trajectories of these poles are determined as functions of groove depth, finding that as this parameter increases they move in the complex wavelength plane to a mode threshold, or cut-off wavelength.
Abstract: The problem of diffraction by a perfectly conducting lamellar grating is examined numerically and analytically by use of a modal expansion technique. At various complex wavelengths, with a positive imaginary part, individual mode amplitudes have poles which give rise to resonance effects in the orders at nearby real wavelengths. These are the well-known resonance anomalies. We determine the trajectories of these poles as functions of groove depth, finding that as this parameter increases they move in the complex wavelength plane to a mode threshold, or cut-off wavelength—from a Rayleigh wavelength in the case of S -polarization and from zero wavelength in the case of P -polarization. It is emphasized that the modal expansion technique is particularly valuable in gaining an understanding of the dynamics of diffraction gratings, and that the resonance poles are perhaps the basic dynamical objects determining their behaviour.
91 citations
TL;DR: The dielectric gratings, which have a surface-relief structure with only several tens of nanometers in peak-to-trough height on a flat metal surface, can efficiently extract radiation modes propagating in free space from the surface-plasmon modes.
Abstract: Efficient outcoupling of surface-plasma waves to radiation modes by use of dielectric diffraction gratings on a flat metallic surface is discussed. The dielectric gratings, which have a surface-relief structure with only several tens of nanometers in peak-to-trough height on a flat metal surface, can efficiently extract radiation modes propagating in free space from the surface-plasmon modes. An outcoupling efficiency of 50% is estimated with the rigorous coupled-wave diffraction theory, and it is confirmed by the experiment.
91 citations
TL;DR: In this article, the surface wrinkles are produced at the surface of a thin film of oil as a result of dielectrophoretic forces, which can be used to optimize either for high-amplitude sinusoidal wrinkles at micrometre-scale pitches or more complex non-sinusoidal profiles with higher Fourier components at longer pitches.
Abstract: Recently, there has been intense interest in photonic devices based on microfluidics, including displays1,2 and refractive tunable microlenses and optical beamsteerers3,4,5 that work using the principle of electrowetting6,7. Here, we report a novel approach to optical devices in which static wrinkles are produced at the surface of a thin film of oil as a result of dielectrophoretic forces8,9,10. We have demonstrated this voltage-programmable surface wrinkling effect in periodic devices with pitch lengths of between 20 and 240 µm and with response times of less than 40 µs. By a careful choice of oils, it is possible to optimize either for high-amplitude sinusoidal wrinkles at micrometre-scale pitches or more complex non-sinusoidal profiles with higher Fourier components at longer pitches. This opens up the possibility of developing rapidly responsive voltage-programmable, polarization-insensitive transmission and reflection diffraction devices and arbitrary surface profile optical devices. Voltage-programmable liquid surface profiles with large amplitudes resulting from dielectrophoresis are demonstrated. The oil interface formed can be ultrastable and static, or rapidly switchable, as shown in the case of a modulated diffraction grating. The scheme provides the possibility for responsive and polarization-insensitive transmission and reflection devices, and for optical interfaces with arbitrary surface profiles.
91 citations
TL;DR: A line of periodic dot structure with an interval of 6.25 μm on a gold thin film was fabricated with a single shot of interfered femtosecond laser beams split by a diffraction beam splitter as mentioned in this paper.
Abstract: A line of periodic dot structure with an interval of 6.25 μm on a gold thin film was fabricated with a single shot of interfered femtosecond laser beams split by a diffraction beam splitter. The total length of the structure was 6 mm. In addition, dot matrix and comb structures were fabricated with transportation of samples at an arbitrary speed during the process. The samples worked as transmission and reflection gratings. In addition, nanowires were fabricated by peeling the comb structure, of which the thickness was 200 nm.
91 citations
TL;DR: Optically controlled planar orientation of liquid crystal molecules with polarized light is used to make phase gratings in liquid crystal media as discussed by the authors, and the electro-optical properties of linear and chirped gratings are discussed.
Abstract: Optically controlled planar orientation of liquid crystal molecules with polarized light is used to make phase gratings in liquid crystal media. The electro‐optical properties of liquid crystal linear and chirped gratings are discussed.
91 citations