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Spatial Solitons in Optically-Induced Gratings  [PDF]
Dragomir Neshev,Elena Ostrovskaya,Yuri Kivshar,Wieslaw Krolikowski
Physics , 2003, DOI: 10.1364/OL.28.000710
Abstract: We study experimentally nonlinear localization effects in optically-induced gratings created by interfering plane waves in a photorefractive crystal. We demonstrate the generation of spatial bright solitons similar to those observed in arrays of coupled optical waveguides. We also create pairs of out-of-phase solitons which resemble ``twisted'' localized states in nonlinear lattices.
Modeling of phase relief of holographic diffraction gratings: application to self-developing photopolymers
M.V. Shovgenyuk,P.A. Hlushak,Yu.M. Kozlovskii,E.A. Tikhonov
Ukrainian Journal of Physical Optics , 2002,
Abstract: The thin holographic diffraction gratings with periodic surface/internal spatial phase modulation are investigated. The dependences of the efficiency in the various diffraction orders are measured and calculated in supposed profiles of phase relief. The calculated results are compared with experimental data of holographic phase gratings recorded in self-developing photopolymers. The numerical values of the phase shift Df of experimental samples are determined. It was found, that the surface relief conforms satisfactory the two-parabolic model, whereas the internal modulation profile in the volume of photopolymer can be well described with two-cylindrical model of the phase relief.
Inscription of local surface relief gratings with a Scanning Near-field Optical Microscope on an azo-polymer film
Bechtold, Ivan H.;Stiller, Burkhard;Brehmer, Ludwig;Oliveira, Elisabeth A. de;
Polímeros , 2006, DOI: 10.1590/S0104-14282006000400012
Abstract: a scanning near-field optical microscope (snom) was used to inscribe locally limited surface relief gratings (srgs) on pdr1m, which is an azo-polymer film. the influence of parameters such as the line scanning time and the line spacing on the amplitude and the period of the gratings is discussed. srgs have been used to orient liquid crystals (lcs), where the lc alignment takes place due to the elastic distortions of the nematic medium close to the surface. in addition, the photoalignment of the azo-chromophores was also used to induce lc alignment. in this work we investigate the use of local sgrs together with the photoalignment to get a local control of the lc alignment properties. the advantage of this method is that it is reversible and the gratings can easily be erased.
Propagation of the electromagnetic field in anisotropic relief gratings

Li Jian-Long,Tang Shi-Hong,Zhu Shi-Fu,Fu Ke-Xiang,

物理学报 , 2010,
Abstract: The propagation of the electromagnetic field in anisotropic relief gratings has been analysis, and the recursive algorithm of RTRA has been extended to the anisotropic medium in this paper. The numerical calculation shows that the space distribution of the electromagnetic field in each sub-micro-layer changes with the varying transmission depth in the relief grating, the space distribution in each sub-micro-layer is more uniformed than that in isotropic grating and the optical parameters of the anisotropic relief grating and the incident beam have a large impact on the space distribution of the electromagnetic field in relief grating and so on.
Spontaneous Formation of Columnar Vortices  [PDF]
Jared P. Whitehead,Beth A. Wingate
Physics , 2012,
Abstract: A fluid dynamics video of the rotating, weakly stratified Boussinesq equations is presented that illustrates the spontaneous formation of columnar vortices in the presence of stochastic, white noise forcing.
Fine structure of Surface Relief Gratings: experiment and a generic stochastic Monte Carlo model of the photoinduced mass transport in azo-polymer  [PDF]
Grzegorz Pawlik,Antoni C. Mitus,Andrzej Miniewicz,Anna Sobolewska
Physics , 2013,
Abstract: We study experimentally and theoretically a double-peak fine structure of Surface Relief Gratings in azo-functionalized poly(etherimide). For the theoretical analysis we develop a stochastic Monte Carlo model for photoinduced mass transport in azobenzene functionalized polymer matrix. The long sought-after transport of polymer chains from bright to dark places of the illumination pattern is demonstrated and characterized, various scenarios for the intertwined processes of build-up of density and SRG gratings are examined. Model predicts that for some azo-functionalized materials double-peak SRG maxima can develop in the permanent, quasi-permanent or transient regimes.
Experimental realization of transverse mode conversion using optically induced transient long-period gratings  [PDF]
Tim Hellwig,Martin Schnack,Till Walbaum,Sven Dobner,Carsten Fallnich
Physics , 2013, DOI: 10.1364/OE.22.024951
Abstract: We present the experimental realization of transverse mode conversion in an optical fiber via an optically induced long-period grating. The transient gratings are generated by femtosecond laser pulses, exploiting the Kerr effect to translate intensity patterns emerging from multimode interference into a spatial refractive index modulation. Since these modulations exist only while the pump beam is present, they can be used for optical switching of transverse modes. As only a localized part of the grating was written at a time and the probe beam was co-propagating with the pump beam the required pulse energies could be reduced to 120\,nJ which is about a factor of 600 lower than in previous quasi-continuous-wave experiments. Accompanying numerical simulations allow a better understanding of the involved effects and show excellent agreement to the experimental results.
Polymer Gratings with Low Surface Relief Based on UV Photo-Polymerization

Zhou Jinbo,Sun Changzheng,Xiong Bing,Wang Jian,Luo Yi,

半导体学报 , 2005,
Abstract: Polymer gratings are fabricated based on photopolymerization.A very low surface relief depth ranging from 12 4 to about 0 7nm has been demonstrated with a refractive index modulation of about 0 010.Such polymer gratings show promising potentials for the fabrication of low-order distributed feedback polymer lasers.
Spontaneous emission and collection efficiency enhancement of single emitters in diamond via plasmonic cavities and gratings  [PDF]
Jennifer T. Choy,Irfan Bulu,Birgit J. M. Hausmann,Erika Janitz,I-Chun Huang,Marko Lon?ar
Physics , 2013, DOI: 10.1063/1.4817397
Abstract: We demonstrate an approach, based on plasmonic apertures and gratings, to enhance the radiative decay rate of single NV centers in diamond, while simultaneously improving their collection efficiency. Our structures are based on metallic resonators formed by surrounding sub-wavelength diamond nanoposts with a silver film, which can enhance the spontaneous emission rate of an embedded NV center. However, the collection efficiency of emitted photons remains low due to losses to surface plasmons and reflections at the diamond-air interface. In this work, we mitigate photon losses into these channels by incorporating grating structures into the plasmonic cavity system.
Spontaneous and Induced Star Formation in the LMC  [PDF]
Y. N. Efremov,B. G. Elmegreen
Physics , 1998,
Abstract: Spontaneous and triggered star formation in the LMC is discussed with data on star clusters ages and positions. The supershell LMC4 and the stellar arcs in the same region are suggested to be triggered by GRBs, the progenitors of which might have escaped the old elliptical cluster NGC1978, close to which are a number of X-ray binaries and the SGR/SNR N49.
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