Search results for "Physics::Optics"
showing 10 items of 1958 documents
Superresolved and field-of-view extended digital holography with particle encoding
2012
We present a new configuration for superresolution (SR) as well as for field-of-view (FOV) extension in a digital holography concept based on random movement of sparse metallic particles. In the SR configuration, the particles are in proximity to the recorded object, while in the FOV configuration, the particles are in proximity to the hologram plane. The particles' movement encodes the high spatial features in the plane of their movement. This high-resolution information can later be decoded by proper numerical postprocessing that either remedies the resolution limitations in the object plane (or the limited NA of the lens) or extends the FOV in the object plane.
All-diffractive achromatic Fourier-transform setup
2009
An achromatic Fourier transformation under broadband converging spherical-wave illumination is optically achieved by use of only two on-axis blazed zone plates. The novel optical configuration provides the achromatic Fraunhofer diffraction pattern of an arbitrary input signal with adjustable magnification. Further analysis of the system permits us to obtain a simple analytical expression to evaluate both the longitudinal and the transversal residual chromatic aberration, resulting in a compact achromatic Fourier transformer with low chromatic errors, even for a wide spectral content of the point source.
White-light array generation with a diffractive lenslet array
1999
Abstract In this paper we present two different optical configurations providing a white-light array generator based on a diffractive lenslet array (DLA). In both cases, starting from a white-light point source we achieve a regularly spaced set of sharp light spots by use of a single DLA and a small number of extra lenses (only one or two). The first optical system permits us to change the separation between the intensity peaks in a tunable way. The second is very compact and consists only of diffractive lens elements. The key question in both set-ups is the use of achromatic Fourier-transform methods. In this way, we achieve, in a first-order approximation, the superposition of the chromat…
Phase conjugation in BaTiO 3 by use of the indirect photorefractive coupling of orthogonally polarized light waves
1998
A phase-conjugate wave is generated when an ordinary (extraordinary) signal wave is mixed with two counterpropagating extraordinary (ordinary) waves in the plane normal to the BaTiO3 polar axis. The photorefractive grating that couples the ordinary and the extraordinary waves appears if the incident waves induce a noticeable conical parametric scattering; this grating is a difference grating of many noisy scattering gratings recorded by means of the usual diffusion-mediated charge transport. For comparable intensities of signal and pump waves this type of nonlinear wave mixing is much more efficient than that which is due to the circular bulk photovoltaic effect.
Buildup of terahertz vector dark-soliton trains from induced modulation instability in highly birefringent optical fiber.
2007
We present the experimental observation of generation of vector dark-soliton pulse trains with terahertz repetition rates in the normal dispersion regime of an optical fiber. The polarization solitons build up from induced cross-phase modulation instability of two orthogonal pumps in a highly birefringent fiber.
Relationship between scanning near-field optical images and local density of photonic states
2001
From numerical calculations based on Green's dyadic formalism, we show that a scanning near-field optical microscope (SNOM) working with a point-like illuminating probe delivers images that contain features directly related to the local density of photonic states (LDOS). More precisely, an unambiguous identification of the partial LDOSs (x, y or z polarized) can be made in the SNOM images when the solid angle of detection reaches 2π sr.
Synchronized photonic modulators driven by surface acoustic waves
2013
Photonic modulators are one of the most important elements of integrated photonics. We have designed, fabricated, and characterized a tunable photonic modulator consisting of two 180 degrees-dephased output waveguide channels, driven by a surface acoustic wave in the GHz frequency range built on (Al,Ga)As. Odd multiples of the fundamental driven frequency are enabled by adjusting the applied acoustic power. A good agreement between theory and experimental results is achieved. The device can be used as a building block for more complex integrated functionalities and can be implemented in several material platforms. (C) 2013 Optical Society of America
Delocalization of Nonlinear Optical Responses in Plasmonic Nanoantennas
2015
Remote excitation and emission of two-photon luminescence and second-harmonic generation are observed in micrometer long gold rod optical antennas upon local illumination with a tightly focused near-infrared femtosecond laser beam. We show that the nonlinear radiations can be emitted from the entire antenna and the measured far-field angular patterns bear the information regarding the nature and origins of the respective nonlinear processes. We demonstrate that the nonlinear responses are transported by the propagating surface plasmon at excitation frequency, enabling thereby polariton-mediated tailoring and design of nonlinear responses.
Designed surface modes propagating along hyperbolic metamaterials
2013
We report on surface-wave propagation (SWP) that occurs in semi-infinite hyperbolic metamaterials whose optical axis is set in the interface plane. In practice it is implemented by a multi-layered metal-dielectric nanostructure that is cut normally to the layers. Our theoretical analysis shows that various conditions can be designed enabling distinct regimes of SWP. We concluded that hybridization of SWP polarization leads to tighter confinement near the interface as compared with conventional surface plasmon polaritons. By using the finite-element method (FEM), we demonstrate that the fields are enhanced on the walls of metallic films, and thus minimizing significantly its presence inside …
Near-field beam displacement at surface plasmon resonance
2011
International audience; A finite-size beam exciting a surface plasmon polariton (SPP) in a prism coupling configuration experiences an in-plane displacement that can be used for the characterization of plasmonic components by means of near-field optical microscopy. We first demonstrate experimentally the existence of this displacement by taking near-field images of finite-width metal strips. Next, the properties of this shift are analyzed in detail. We investigate the dynamic of the near-field shift for an incident Gaussian beam as a function of illumination conditions. For beams with a narrow spectrum, we propose a straightforward derivation showing that the displacement depends on the ave…