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Author

Ignacio Moreno

Bio: Ignacio Moreno is an academic researcher from Universidad Miguel Hernández de Elche. The author has contributed to research in topics: Polarization (waves) & Spatial light modulator. The author has an hindex of 32, co-authored 254 publications receiving 4175 citations. Previous affiliations of Ignacio Moreno include Autonomous University of Barcelona & University of Alicante.


Papers
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Journal ArticleDOI
TL;DR: A new, to the knowledge, technique for encoding amplitude information onto a phase-only filter with a single liquid-crystal spatial light modulator, effectively allowing for amplitude modulation of either the first-order or the zero-order diffracted light.
Abstract: We report a new, to our knowledge, technique for encoding amplitude information onto a phase-only filter with a single liquid-crystal spatial light modulator. In our approach we spatially modulate the phase that is encoded onto the filter and, consequently, spatially modify the diffraction efficiency of the filter. Light that is not diffracted into the first order is sent into the zero order, effectively allowing for amplitude modulation of either the first-order or the zero-order diffracted light. This technique has several applications in both optical pattern recognition and image processing, including amplitude modulation and inverse filters. Experimental results are included for the new technique.

452 citations

Journal ArticleDOI
TL;DR: By combining previously reported techniques, this work can achieve complete amplitude, phase and polarization control for the diffracted light that allows the creation of arbitrary diffractive optical elements including polarization control.
Abstract: We present a method to generate complete arbitrary spatially variant polarization modulation of a light beam by means of a parallel aligned nematic liquid crystal spatial light modulator (SLM). We first analyze the polarization modulation properties in a transmission mode. We encode diffraction gratings onto the SLM and show how to achieve partial polarization control of the zero order transmitted light. We then extend the technique to a double modulation scheme, which is implemented using a single SLM divided in two areas in a reflective configuration. The polarization states of the transmitted beam from the first pass through the first area are rotated using two passes through a quarter wave plate. The beam then passes through the second area of the SLM where additional polarization information can be encoded. By combining previously reported techniques, we can achieve complete amplitude, phase and polarization control for the diffracted light that allows the creation of arbitrary diffractive optical elements including polarization control. Theoretical analysis based on the Jones matrix formalism, as well as excellent experimental results are presented.

168 citations

Journal ArticleDOI
TL;DR: It is shown that superior phase-only operation can be obtained over a given operating range for the LCD compared with other approaches and that the eigenvectors are elliptically polarized.
Abstract: We derive theoretical expressions for the eigenvalues and the eigenvectors for a twisted-nematic liquid-crystal display (LCD) as a function of the twist angle and the birefringence by use of the Jones-matrix formalism. These polarization eigenvectors are of particular interest for phase-only transmission because they propagate unchanged through the display. We find that the eigenvectors are elliptically polarized and that the ellipticity changes as a function of the birefringence of the LCD (which is proportional to the external voltage applied to the display). We can define an average eigenvector over a desired range for the applied voltage. We show, using Jones matrices, how this average eigenvector can be generated using a quarter-wave plate and a linear polarizer having appropriate orientation angles. Using this average eigenvector, we show that superior phase-only operation can be obtained over a given operating range for the LCD compared with other approaches.

152 citations

Journal ArticleDOI
TL;DR: Evidence of the temporal fluctuations of the phase modulation property of a liquid crystal on silicon (LCoS) display is provided, and its effect when the device is used for displaying a diffractive optical element is analyzed.
Abstract: In this paper we provide evidence of the temporal fluctuations of the phase modulation property of a liquid crystal on silicon (LCoS) display, and we analyze its effect when the device is used for displaying a diffractive optical element. We use a commercial twisted nematic LCoS display configured to produce a phase-only modulation, and we provide time resolved measurements of the diffraction efficiency that show rapid fluctuations of the phase modulation, in the millisecond order. We analyze how these fluctuations have to be considered in two typical methods for the characterization of the phase modulation: two beam interference and diffraction from a binary grating. We finally provide experimental results on the use of this device for displaying a computer generated hologram. A reduction of the modulation diffraction efficiency results from the phase modulation fluctuation.

148 citations

Journal ArticleDOI
TL;DR: In this article, a method to perform a predictive search for a given amplitude and phase modulation response in twisted nematic liquid crystal displays is presented, based on a simple physical model that considers the effect of liquid-crystal layers located in the vicinity of the edges, which are not able to tilt.
Abstract: A method to perform a predictive search for a given amplitude and phase modulation response in twisted nematic liquid crystal displays is presented. The algorithm is based on a simple physical model that we recently proposed and that considers the effect of liquid-crystal layers located in the vicinity of the edges, which are not able to tilt. This model was demonstrated to explain accurately the experimental transmittance modulation curves. Here the model is applied to perform a predictive search for an optimized modulation by changing the input and output polarization configurations. A generalized configuration to generate and detect elliptically polarized light is proposed. The method is applied for seeking two different configurations useful for optical image processors: phase-only modulation and amplitude-only modulation. The excellent agreement with the experimental measurements validates the potential of the proposed method.

134 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Book
01 Jan 1960

1,106 citations

Journal ArticleDOI
19 Oct 2012-Science
TL;DR: Silicon-integrated optical vortex emitters are demonstrated, using angular gratings to extract light confined in whispering gallery modes with high OAM into free-space beams with well-controlled amounts of OAM, confirming the theoretical prediction that the emitted beams carry exactly defined and adjustable OAM.
Abstract: Emerging applications based on optical beams carrying orbital angular momentum (OAM) will probably require photonic integrated devices and circuits for miniaturization, improved performance, and enhanced functionality. We demonstrate silicon-integrated optical vortex emitters, using angular gratings to extract light confined in whispering gallery modes with high OAM into free-space beams with well-controlled amounts of OAM. The smallest device has a radius of 3.9 micrometers. Experimental characterization confirms the theoretical prediction that the emitted beams carry exactly defined and adjustable OAM. Fabrication of integrated arrays and demonstration of simultaneous emission of multiple identical optical vortices provide the potential for large-scale integration of optical vortex emitters on complementary metal-oxide–semiconductor compatible silicon chips for wide-ranging applications.

782 citations

Journal ArticleDOI
TL;DR: A theoretical analysis and experimentally demonstrate a Pancharatnam-Berry phase-based diffraction grating for laser radiation at a wavelength of 10.6microm.
Abstract: Space-variant Pancharatnam-Berry phase optical elements based on computer-generated subwavelength gratings are presented. By continuously controlling the local orientation and period of the grating we can achieve any desired phase element. We present a theoretical analysis and experimentally demonstrate a Pancharatnam-Berry phase-based diffraction grating for laser radiation at a wavelength of 10.6microm.

664 citations

Journal ArticleDOI
TL;DR: In this paper, the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face, as well as the exciting prospects for the future that are yet to be realized.
Abstract: Structured light refers to the generation and application of custom light fields. As the tools and technology to create and detect structured light have evolved, steadily the applications have begun to emerge. This roadmap touches on the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face. Collectively the roadmap outlines the venerable nature of structured light research and the exciting prospects for the future that are yet to be realized.

639 citations