The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Erez Hasman - One of the best experts on this subject based on the ideXlab platform.
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Random Topological Defects-Induced Spin-Enabled Photonic Transport by Metasurfaces
2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO Europe-EQEC), 2019Co-Authors: Bo Wang, Vladimir Kleiner, Elhanan Maguid, Michael Yannai, Erez HasmanAbstract:Over the past decades, topology has provided unique insights into numerous physical phenomena [1, 2]. Here, we report on observation of spin-enabled photonic transport induced by creation of bound vortex pairs (VPs) and unbound vortices from geometric Phase metasurfaces (GPMs). The GPM is consisted of anisotropic nanoantennas oriented in an on-demand profile, providing vast opportunities to observe intriguing physical phenomena such as topological defects (TDs) [3], multiple wave-front shaping [4], photonic transition [5], and single photon entanglement [6]. We achieve topological behaviour by randomly inserting Geometrical Phase defects into the GPM system with different concentrations (Fig.1 a, b and c). As a result, photonic bound VPs - two closely located TDs with topological charges of +1 and -1 - are observed in the near field of the metasurfaces by interference patterns (Fig.1 d). The observed number of VPs increases with the defect concentration of metasurfaces, up to a point where the vortices are unbound. The geometric Phase induces a spin-orbit interaction, which enables the observation of the photonic spin Hall effect (PSHE) in the bound VPs state and a photonic random Rashba effect in the unbound vortices state. We found that the PSHE originates from a single spin-dependent VP. Therefore, when isolated VPs were randomly aligned in the near field, the spin-deflection in momentum space obeys a simple vector summation rule dictating the orientation of the PSHE from these VPs (Fig. 1 e). A continual increase in the number of VPs resulted in random Phase fluctuations - the proliferation of unbound vortices. Accordingly, the momentum space is manifested by numerous spin-dependent modes beyond the diffraction limit, until these modes fill the entire momentum space, exhibiting a random Rashba effect.
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Spatial-polarization state scrambling for image encryption obtained with subwavelength gratings
(CLEO). Conference on Lasers and Electro-Optics 2005., 2005Co-Authors: Gabriel Biener, V. Kleiner, Erez HasmanAbstract:We present an optical encryption/decryption methods based on Geometrical Phase produced by space-variant polarization manipulation. The elements are formed by use of computer-generated space-variant subwavelength dielectric gratings.
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Geometrical Phase image encryption obtained with space variant subwavelength gratings
Optics Letters, 2005Co-Authors: Gabriel Biener, Vladimir Kleiner, Erez HasmanAbstract:An optical encryption method based on a Geometrical Phase produced by space-variant polarization manipulation is presented. The decrypted picture is retrieved either by a polarization measurement of the beam emerging from the encrypted element or by a single intensity measurement of the beam transmitted through the encrypted element followed by an optical key element. Both elements are realized by use of computer-generated space-variant subwavelength dielectric gratings. Theoretical analyses of the optical concept are presented along with experimental results.
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Polarization dependent focusing lens by use of quantized Pancharatnam-Berry Phase diffractive optics
Applied Physics Letters, 2003Co-Authors: Erez Hasman, Gabriel Biener, Vladimir Kleiner, Avi NivAbstract:Quantized Pancharatnam–Berry Phase diffractive optics using computer-generated space-variant subwavelength dielectricgrating is presented. The formation of the Geometrical Phase is done by discrete orientation of the local subwavelength grating. We discuss a theoretical analysis and experimentally demonstrate a quantized Geometrical blazed Phase of polarizationdiffraction grating, as well as polarization dependent focusing lens for infrared radiation at wavelength 10.6 μm.
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Optical elements based on space-variant Pancharatnam-Berry Phase manipulation
2002 Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, 2002Co-Authors: Z. Bomzon, Gabriel Biener, V. Kleiner, Erez HasmanAbstract:Summary form only given. We demonstrate novel optical Phase elements based on the space-domain Pancharatnam-Berry Phase. Unlike diffractive and refractive elements, the Phase is not introduced through optical path differences, but results from the Geometrical Phase that accompanies space variant polarization manipulation. We analyze Pancharatnam-Berry Phase optical elements (PBOEs) that consist of space varying, (transversely inhomogeneous) waveplates with constant retardation, and space-varying fast axis orientation.
Lew Rabenberg - One of the best experts on this subject based on the ideXlab platform.
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effects of strain gradients on strain measurements using Geometrical Phase analysis in the transmission electron microscope
Ultramicroscopy, 2008Co-Authors: Jayhoon Chung, Lew RabenbergAbstract:Abstract An analysis of the effects of lens aberrations on the Phase contrast images used for strain measurement by geometric Phase analysis (GPA) in the TEM shows that errors may result when strain gradients are present and when ∇χ≠0 at the reciprocal lattice spacing used for the analysis. This conclusion is demonstrated experimentally using a model specimen consisting of a strained Si layer grown epitaxially on a Si–Ge alloy substrate. Image simulations for this model specimen show that strain gradients can introduce oscillations in strain maps when the defocus is not optimized for GPA. This work also makes it possible to identify other potential sources of error in GPA.
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local strain measurement in a strain engineered complementary metal oxide semiconductor device by Geometrical Phase analysis in the transmission electron microscope
Applied Physics Letters, 2008Co-Authors: Jayhoon Chung, Guoda Lian, Lew RabenbergAbstract:Local strains in the channel and source/drain (S/D) of an advanced complementary metal-oxide-semiconductor device were measured by the geometric Phase analysis applied to high resolution transmission electron microscope images. Two-dimensional strain maps were reconstructed for a 45nm p-type metal-oxide-semiconductor device which was strain-engineered using a recessed Si0.82Ge0.18 S/D. Lateral strains were uniform across the channel but vertical strains were found to vary considerably in the channel. Measured strains were used to estimate stresses and hole mobility enhancements.
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measurement of incomplete strain relaxation in a silicon heteroepitaxial film by Geometrical Phase analysis in the transmission electron microscope
Applied Physics Letters, 2007Co-Authors: Jayhoon Chung, Lew RabenbergAbstract:Relaxation of strain by a partial dislocation and stacking fault in a strained Si film was characterized using geometric Phase analysis of high-resolution transmission electron microscope (HRTEM) images. Movement of a 60° glide dislocation from the free surface to the film-substrate interface created a complex state of strain in the film. HRTEM image analysis was used to produce a quantitative measure of the atomic displacement fields that could be used as input to finite-element simulations of stress distributions and resulting affects on band structures.
Jayhoon Chung - One of the best experts on this subject based on the ideXlab platform.
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effects of strain gradients on strain measurements using Geometrical Phase analysis in the transmission electron microscope
Ultramicroscopy, 2008Co-Authors: Jayhoon Chung, Lew RabenbergAbstract:Abstract An analysis of the effects of lens aberrations on the Phase contrast images used for strain measurement by geometric Phase analysis (GPA) in the TEM shows that errors may result when strain gradients are present and when ∇χ≠0 at the reciprocal lattice spacing used for the analysis. This conclusion is demonstrated experimentally using a model specimen consisting of a strained Si layer grown epitaxially on a Si–Ge alloy substrate. Image simulations for this model specimen show that strain gradients can introduce oscillations in strain maps when the defocus is not optimized for GPA. This work also makes it possible to identify other potential sources of error in GPA.
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local strain measurement in a strain engineered complementary metal oxide semiconductor device by Geometrical Phase analysis in the transmission electron microscope
Applied Physics Letters, 2008Co-Authors: Jayhoon Chung, Guoda Lian, Lew RabenbergAbstract:Local strains in the channel and source/drain (S/D) of an advanced complementary metal-oxide-semiconductor device were measured by the geometric Phase analysis applied to high resolution transmission electron microscope images. Two-dimensional strain maps were reconstructed for a 45nm p-type metal-oxide-semiconductor device which was strain-engineered using a recessed Si0.82Ge0.18 S/D. Lateral strains were uniform across the channel but vertical strains were found to vary considerably in the channel. Measured strains were used to estimate stresses and hole mobility enhancements.
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measurement of incomplete strain relaxation in a silicon heteroepitaxial film by Geometrical Phase analysis in the transmission electron microscope
Applied Physics Letters, 2007Co-Authors: Jayhoon Chung, Lew RabenbergAbstract:Relaxation of strain by a partial dislocation and stacking fault in a strained Si film was characterized using geometric Phase analysis of high-resolution transmission electron microscope (HRTEM) images. Movement of a 60° glide dislocation from the free surface to the film-substrate interface created a complex state of strain in the film. HRTEM image analysis was used to produce a quantitative measure of the atomic displacement fields that could be used as input to finite-element simulations of stress distributions and resulting affects on band structures.
Gabriel Biener - One of the best experts on this subject based on the ideXlab platform.
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Spatial-polarization state scrambling for image encryption obtained with subwavelength gratings
(CLEO). Conference on Lasers and Electro-Optics 2005., 2005Co-Authors: Gabriel Biener, V. Kleiner, Erez HasmanAbstract:We present an optical encryption/decryption methods based on Geometrical Phase produced by space-variant polarization manipulation. The elements are formed by use of computer-generated space-variant subwavelength dielectric gratings.
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Geometrical Phase image encryption obtained with space variant subwavelength gratings
Optics Letters, 2005Co-Authors: Gabriel Biener, Vladimir Kleiner, Erez HasmanAbstract:An optical encryption method based on a Geometrical Phase produced by space-variant polarization manipulation is presented. The decrypted picture is retrieved either by a polarization measurement of the beam emerging from the encrypted element or by a single intensity measurement of the beam transmitted through the encrypted element followed by an optical key element. Both elements are realized by use of computer-generated space-variant subwavelength dielectric gratings. Theoretical analyses of the optical concept are presented along with experimental results.
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Polarization dependent focusing lens by use of quantized Pancharatnam-Berry Phase diffractive optics
Applied Physics Letters, 2003Co-Authors: Erez Hasman, Gabriel Biener, Vladimir Kleiner, Avi NivAbstract:Quantized Pancharatnam–Berry Phase diffractive optics using computer-generated space-variant subwavelength dielectricgrating is presented. The formation of the Geometrical Phase is done by discrete orientation of the local subwavelength grating. We discuss a theoretical analysis and experimentally demonstrate a quantized Geometrical blazed Phase of polarizationdiffraction grating, as well as polarization dependent focusing lens for infrared radiation at wavelength 10.6 μm.
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Optical elements based on space-variant Pancharatnam-Berry Phase manipulation
2002 Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, 2002Co-Authors: Z. Bomzon, Gabriel Biener, V. Kleiner, Erez HasmanAbstract:Summary form only given. We demonstrate novel optical Phase elements based on the space-domain Pancharatnam-Berry Phase. Unlike diffractive and refractive elements, the Phase is not introduced through optical path differences, but results from the Geometrical Phase that accompanies space variant polarization manipulation. We analyze Pancharatnam-Berry Phase optical elements (PBOEs) that consist of space varying, (transversely inhomogeneous) waveplates with constant retardation, and space-varying fast axis orientation.
Wei Zhang - One of the best experts on this subject based on the ideXlab platform.
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effect of reference region size on strain measurements using Geometrical Phase analysis
Journal of Microscopy, 2020Co-Authors: Y Wang, Xin Ge, Wei ZhangAbstract:: Geometrical Phase analysis (GPA) is typically a powerful tool to investigate the deformation in high resolution transmission electron microscopy images and has been used in various fields. During GPA, strain components are calculated relative to an undistorted reference region. In the present work, the effect of reference region size on strain measurements has been investigated. Experimental measurements on a locally distorted gold nanoparticle exhibited that a small reference region below the GPA spatial resolution can introduce an inaccuracy in the measured displacement field, which appears as a significant increase in measured strains and severe fluctuation in Phase images. The inaccuracy may be ascribed to an error of insufficient sampling. Our results suggest that a small reference region below the GPA spatial resolution should be avoided during GPA. This prerequisite should be paid more attention to during strain measurement on nanoparticles.