Two-dimensional photonic crystals in antimony-based films fabricated by holography

In this work, we demonstrated the fabrication of two-dimensional (2D) photonic crystals layers (2D-PCLs) by combining holographic recording and the evaporation of antimony-based glasses. Such materials present high refractive indices that can be tuned from 1.8 to 2.4, depending on the film composition; thus, they are interesting dielectric materials for fabrication of 2D-PCLs. The good quality of the obtained samples allowed the measurement of their PC properties through the well-defined Fano resonances that appear in the transmittance spectrum measurements at different incidence angles. The experimental results are in good agreement with the calculated band diagram for the hexagonal asymmetric structure. (C) 2008 American Institute of Physics.

Proposal for underwater structural analysis using the techniques of ESPI and digital holography

The purpose of this article is to study the application of the holographic interferometry techniques in the structural analysis of submarine environment. These techniques are widely used today, with applications in many areas. Nevertheless, its application in submarine environments presents some challenges. The application of two techniques, electronic speckle pattern interferometry (ESPI) and digital holography, comparison of advantages and disadvantages of each of them is presented. A brief study is done on the influence of water properties and the optical effects due to suspended particles as well as possible solutions to minimize these problems. (C) 2009 Elsevier Ltd. All rights reserved.

Denisiuk-type reflection holography display with sillenite crystals for imaging and interferometry of small objects

A novel setup for imaging and interferometry through reflection holography with Bi12TiPO20(BTO) sillenite photorefractive crystals is proposed. A variation of the lensless Denisiuk arrangement was developed resulting in a compact, robust and simple interferometer. A red He-Ne laser was used as light source and the holographic recording occurred by diffusion with the grating vector parallel to the crystal [0 0 1]-axis. In order to enhance the holographic image quality and reduce noise a polarizing beam splitter (PBS) was positioned at the BTO input and the crystal was tilted around the [0 0 1]-axis. This enabled the orthogonally polarized transmission and diffracted beams to be separated by the PBS, providing the holographic image only. The possibility of performing deformation and strain analysis as well as vibration measurement of small objects was demonstrated. (C) 2007 Elsevier B.V. All rights reserved.

Large N phases, gravitational instantons and the nuts and bolts of AdS holography

Recent results in the literature concerning holography indicate that the thermodynamics of quantum gravity (at least with a negative cosmological constant) can be modeled by the large N thermodynamics of quantum field theory. We emphasize that this suggests a completely unitary evolution of processes in quantum gravity, including black hole formation and decay, and even more extreme examples involving topology change. As concrete examples which show that this correspondence holds even when the space-time is only locally asymptotically AdS, we compute the thermodynamical phase structure of the AdS-Taub-NUT and AdS-Taub-bolt spacetimes, and compare them to a (2+1)-dimensional conformal field theory (at large N) compactified on a squashed three-sphere and on the twisted plane.

Charged AdS black holes and catastrophic holography

We compute the properties of a class of charged black holes in antide Sitter space-time, in diverse dimensions. These black holes are solutions of consistent Einstein-Maxwell truncations of gauged supergravities, which are shown to arise from the inclusion of rotation in the transverse space. We uncover rich thermodynamic phase structures for these systems, which display classic critical phenomena, including structures isomorphic to the van der WaalsMaxwell liquid-gas system. In that case, the phases are controlled by the universal cusp and swallowtail shapes familiar from catastrophe theory. All of the thermodynamics is consistent with field theory interpretations via holography, where the dual field theories can sometimes be found on the world volumes of coincident rotating branes.

Holography, thermodynamics and fluctuations of charged AdS black holes

rg model with A3 potential. The holographically dual field theories provide the description of the microscopic degrees of freedom which underlie all of the thermodynamics, as can be seen by examining the form of the microscopic fluctuations.

A digital holography technique for generating beams with arbitrary polarization and shape

A method for generating beams with arbitrary polarization and shape is proposed. Our design requires the use of a Mach-Zehnder set-up combined with translucent liquid crystal displays in each arm of the interferometer; in this way, independent manipulation of each transverse beam components is possible. The target of this communication is to develop a numerical procedure for calculating the holograms required for dynamically encode any amplitude value and polarization state in each point of the wavefront. Several examples demonstrating the capabilities of the method are provided.

Theoretical and experimental optical holography

The intent of this paper is to present an analysis of optical holography. Both the physical theory behind holography and the experimental techniques used in making holograms will be presented. To accomplish this goal, the paper is divided into two independent sections: the theoretical section followed by the experimental section. Each section is intended to be a complete unit. The Theoretical Section is an exposure to the theory behind holography. This consists of a review of the concepts of interference and diffraction. followed by a brief review of partial coherence. The remaining part of the Theoretical Section is devoted to the mathematical analysis of optical holography. The Experimental Section begins with an introduction to the equipment and facilities currently available for optical holography at Colby College. Holographic procedures is dominated by the description of transmission holography (v.s. reflection. or white-light. holography). After these general holographic procedures a few variations on the basic transmission hologram are presented. The experimental section will end with an introduction to holographic interferometry, a major application of holographic techniques.

Multi-wavelength holography in Bi12TiO20 crystals: Applications in refractometry

We present a recent development in holography with multimode, large free-spectral range (FSR) diode lasers in photorefractive sillenite crystals. A novel refractometry method based on this type of holographic recording in Bi12TiO20 (BTO) crystals is proposed. The holographic image of a prism-shaped transparent sample appears covered of interference fringes, and as the sample is properly translated, the fringes run along the holographic image. An expression providing the refractive index of the medium as a function of the sample displacement and the correspondent number of running fringes was derived. The refractive indexes of optical (BK7) glass, ethanol, hexan, cumene and aqueous solution of NaCl with different concentrations were measured in order to test the method. The obtained results are in good agreement with the ones reported in literature or measured by us using a commercial Abbe refractometre. (c) 2006 Elsevier B.V. All rights reserved.

Advances in phase-stepping real-time holography using photorefractive sillenite crystals

This work presents a review of recent developments in phase-stepping real-time holographic interferometry with photorefractive sillenite crystals. Quantitative results are shown in micro-rotation, micro-displacement, and micro-deformation measurements, and in wave-optics and surface analysis as well. The phase stepping was carried out in a four-frame process and the resulting phase map was unwrapped by applying a sin/cos filter. The experimental results are in good agreement with the ones obtained through other means, showing the promising potentialities of phase-stepping real-time holographic interferometry for in situ visualisation, monitoring and analysis in non-destructive testing.

Denisiuk-type reflection holography display with sillenite crystals for imaging and interferometry of small objects

A novel setup for imaging and interferometry through reflection holography with Bi12TiPO20(BTO) sillenite photorefractive crystals is proposed. A variation of the lensless Denisiuk arrangement was developed resulting in a compact, robust and simple interferometer. A red He-Ne laser was used as light source and the holographic recording occurred by diffusion with the grating vector parallel to the crystal [0 0 1]-axis. In order to enhance the holographic image quality and reduce noise a polarizing beam splitter (PBS) was positioned at the BTO input and the crystal was tilted around the [0 0 1]-axis. This enabled the orthogonally polarized transmission and diffracted beams to be separated by the PBS, providing the holographic image only. The possibility of performing deformation and strain analysis as well as vibration measurement of small objects was demonstrated. (C) 2007 Elsevier B.V. All rights reserved.

Measurement of low-derivative surface lenses by two-laser holography with Bi12TiO20 crystals

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Two-dimensional photonic crystals in antimony-based films fabricated by holography

In this work, we demonstrated the fabrication of two-dimensional (2D) photonic crystals layers (2D-PCLs) by combining holographic recording and the evaporation of antimony-based glasses. Such materials present high refractive indices that can be tuned from 1.8 to 2.4, depending on the film composition; thus, they are interesting dielectric materials for fabrication of 2D-PCLs. The good quality of the obtained samples allowed the measurement of their PC properties through the well-defined Fano resonances that appear in the transmittance spectrum measurements at different incidence angles. The experimental results are in good agreement with the calculated band diagram for the hexagonal asymmetric structure. (C) 2008 American Institute of Physics.

Profilometry of semiconductor components by two-colour holography with Bi12TiO20 crystals

We studied the shape measurement of semiconductor components by holography with photorefractive Bi12TiO20 crystal as holographic medium and two diode lasers emitting in the red region as light sources. By properly tuning and aligning the lasers a synthetic wavelength was generated and the resulting holographic image of the studied object appears modulated by cos2-contour fringes which correspond to the intersection of the object surface with planes of constant elevation. The position of such planes as a function of the illuminating beam angle and the tuning of the lasers was studied, as well as the fringe visibility. The fringe evaluation was performed by the four stepping technique for phase mapping and through the branch-cut method for phase unwrapping. A damage in an integrated circuit was analysed as well as the relief of a coin was measured, and a precision up to 10 μm was estimated. © 2009 SPIE.

Anti-de Sitter holography in di?erent coordinates

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)