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© 2013 Optical Society of America. Financial support from the National Research Council of Canada and Spanish Ministry of Economy (TEC2008-04105 and TEC2011-23629) is acknowledged., We report a spatial heterodyne Fourier-transform spectrometer implemented with an array of optical fiber interferometers. This configuration generates a wavelength-dependent stationary interferogram from which the input spectrum is retrieved in a single shot without scanning elements. Furthermore, fabrication and experimental deviations from the ideal behavior of the device are corrected by spectral inversion algorithms. The spectral resolution of our system can be readily scaled up by incorporating longer optical fiber delays, providing a pathway toward surpassing current spectroscopy resolution limits., National Research Council, Canada, Ministerio de Economía, España, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

©2011 Optical Society of America. We thank J. A. Rodrigo and R. Weigand for helpful discussions. The financial support of the Spanish Ministry of Innovation and Science, under grant TEC2008-1045 is acknowledged. One of us (M.P. Hernandez-Garay) acknowledges the MAEC-AECID (Spain) and CONACyT (Mexico) grants, P. Vaveliuk is grateful to CNPq (Brazilian federal grant agency) for financial support. We thank to Chemical Reaction Dynamics and Femtochemistry Group: J. G. Izquierdo and L. Bañares (Spanish Ministry of Science and Innovation (MICINN) through Grant CTQ2008-02578/BQU, and Consolider SAUUL CSD2007-00013). Finally, the authors gratefully the reviewers’s suggestions., The majority of the applications of ultrashort laser pulses require a control of its spectral bandwidth. In this paper we show the capability of volume phase holographic gratings recorded in photopolymerizable glasses for spectral pulse reshaping of ultrashort laser pulses originated in an Amplified Ti: Sapphire laser system and its second harmonic. Gratings with high laser induce damage threshold (LIDT) allowing wide spectral bandwidth operability satisfy these demands. We have performed LIDT testing in the photopolymerizable glass showing that the sample remains unaltered after more than 10 million pulses with 0,75 TW/cm^2 at 1 KHz repetition rate. Furthermore, it has been developed a theoretical model, as an extension of the Kogelnik's theory, providing key gratings design for bandwidth operability. The main features of the diffracted beams are in agreement with the model, showing that non-linear effects are negligible in this material up to the fluence threshold for laser induced damage. The high versatility of the grating design along with the excellent LIDT indicates that this material is a promising candidate for ultrashort laser pulses manipulations., Ministerio de Ciencia e Innovación-MICINN, España, Ministerio de Asuntos Exteriores y de Cooperación, España, Consejo Nacional de Ciencia y Tecnología CONACyT, México, CNPq (Brazilian federal grant agency), Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 1996 Optical Society of America. The support of this study by the National Aerospace Institute Ministry of Defense) and the partial financial support from the Comisión Interministerial de Ciencia y Tecnología (Ministry of Education and Science) are acknowledged., The theoretical model for an off-Bragg on-axis conversion between a Gaussian beam with cylindrical phase function and a plane wave by a volume aperiodic nonplanar inhomogeneous holographic grating is presented. A two-wave first-order coupled-wave theoretical framework is adopted. Analytical solutions for the amplitudes of two space harmonics of the field inside the grating zone are derived. Both the chromatic and the geometric deviations from the exact Bragg condition are studied. Numerical evaluations show that some anomalous phenomena (Pendellösung fringes, angle amplification effect, achromatism) can arise. High diffraction efficiency (≈1) is predicted even for relatively large off-Bragg deviations. The deterioration of the reconstruction fidelity due to the Pendellösung effect is discussed., Instituto Nacional de Técnica Aeroespacial (INTA), España, Ministerio de Defensa, España, Comisión Interministerial de Ciencia y Tecnología, España, Ministerio de Educación y Ciencia (MEC), España, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 1995 Optical Society of America., The spatial impulse response of a single variable-cross-section photoreceptor has been characterized assuming the incoming radiation to be an initial field propagating under confinement conditions inside the receptor. By application of Fourier analysis the total transfer function is determined. Both the outer and the inner segments are characterized as low-pass filters. The dependence of the transfer function on the modal parameter is analyzed., Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 1997 Optical Society of America. The Optical Society (OSA) Annual Meeting (1995. Portland, Oregón, EE.UU.). Congress of the International Comission for Optics (ICO) (17º. 1996. Taejon, Corea del Sur). This work was supported in part by the School of Optometry of the University of Missouri–St. Louis (UMSL). A UMSL research grant is also gratefully acknowledged. We also thank Jerry Christensen, Dean, School of Optometry, USML, for support during the initial stages of this research program. Additional financial assistance from the Spanish Ministry of Education and Science (DGICYT) under project PR94-362 to M. L. Calvo is also acknowledged. Partial results were presented at the OSA Annual Meeting (Portland, Oregon, October 1995) and at the ICO-XVII Congress (Taejon, Korea, August 1996). The authors also thank an anonymous referee for a careful review and R. F. Álvarez-Estrada and G. F. Calvo for helpful suggestions and discussions., We apply techniques of optimal-control theory, namely, the methods of dynamic programming, to the problem of light propagation in optical waveguides. This formulation is equivalent to the resolution of an eikonal equation. We illustrate this optimization technique for the case of an ideal parabolic refractive-index-profile distribution. We discuss the possibility of extending this procedure to other types of optical waveguides and optical media., School of Optometry of the University of Missouri–St. Louis (UMSL), EE. UU., Subdirección General de Proyectos (DGICYT), España, Ministerio de Educación y Ciencia (MEC), España, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 1987 Optical Society of America. This work was supported in part by grant EY03674 from the National Eye Institute, National Institutes of Health, Bethesda, Md. M. L. Calvo was supported by a grant from the U.S.- Spain Joint Committee for Scientific and Technological Cooperation Program. We thank J. M. Enoch for support and encouragement., An exact formulation of the electromagnetic field striking an optical waveguide is presented and compared with the decomposition relationship used in the literature. The expression for the critical angle is derived as a natural consequence of this formulation. Equations for the total fraction of power confined within a waveguide are derived and analyzed for the special case of absorbing waveguides. An explicit expression is derived for the fraction of energy confined within a waveguide supporting two sets of modes., National Eye Institute (NEI), EE.UU., National Institutes of Health (NIH), EE.UU., U.S.-Spain Joint Committee for Scientific and Technological Cooperation Program, (España - EE.UU.), Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2000 Optical Society of America. International Conference on Optical Science and Applications for Sustainable Development (2000. Dakar, Senegal). This research was financially supported by the Rectorate of the Complutense University of Madrid (UCM), under Multidisciplinary Project PR486/97-7477/97. T. Alieva is grateful for a grant from UCM. Partial results of this study were presented at the International Conference on Optical Science and Applications for Sustainable Development, Dakar (Senegal), April 10–14, 2000., In this study the general algorithm for the fractionalization of the linear cyclic integral transforms is established. It is shown that there are an infinite number of continuous fractional transforms related to a given cyclic integral transform. The main properties of the fractional transforms used in optics are considered. As an example, two different types of fractional Hartley transform are introduced, and the experimental setups for their optical implementation are proposed., Universidad Complutense de Madrid (UCM), Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 1987 Optical Society of America. M. L. Calvo acknowledges the partial financial support received from the Spain-USA Joint Committee for Scientific and Technical Cooperation and is grateful to Jay M. Enoch for his kind hospitality at the School of Optometry, University of California at Berkeley. R. F. Alvarez-Estrada acknowledges the partial financial support received from the Council for International Exchange of Scholars through a Fulbright-MEC Fellowship and is grateful to B. Zumino for his kind hospitality at the Theoretical Physics Group, Lawrence Berkeley Laboratory., A three-dimensional analysis of bending losses in dielectric optical waveguides is presented. It constitutes a nontrivial generalization of previous two- and three-dimensional studies by other authors. Our analysis is based on homogeneous integral equations for the total radiation field and suitable asymptotic approximations for Green’s functions. A key role is played by a new three-dimensional approximation for a relevant Bessel function with large order and argument (the former being larger than the latter). A nontrivial check of the consistency of all those approximations is given. General formulas are presented for the radiated field and the energy flow and for a bending-loss coefficient in three dimensions. Numerical results are also given, in order to assess the difference between the results of other authors and ours. Such a difference is rather small for monomode behavior near cutoff, increases as the behavior of the waveguide changes from monomode to multimode, and decreases as the parameter V increases for a given core radius and propagation mode., Spain-USA Joint Committee for Scientific and Technical Cooperation (España, EE.UU.), Council for International Exchange of Scholars (CIES), EE.UU., Comisión de Intercambio Cultural, Educativo y Científico (Comisión Fulbright), España, EE.UU., Ministerio de Educación y Ciencia (MEC), España, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2010 Optical Society of America. P. V. and F. M. acknowledge financial support from CNPq (Brazilian federal grant agency). The partial financial support of the Spanish Ministry of Innovation and Science, under project TEC2008-04105is acknowledged., A q-plate is a stratified medium composed of a uniaxial nematic liquid crystal with an inhomogeneous orientation of the optical axis possessing a topological charge q, which looks promising as a switching device. This work reports an approach to diagonalizing the dielectric tensor in q-plates, giving a detailed study of nontrivial tensor coordinate transformations. The relationship between the diagonal dielectric tensor and the topological charge of the plate is established. From that, the dielectric tensor for a given q-plate can be explicitly calculated in a convenient frame, and hence the field propagation equations can be derived. These studies establish a theoretical basis that could further deepen the research on these particular structures for nonconventional manipulation of the light., CNPq (Brazilian federal grant agency), Ministerio de Ciencia e Innovación (MICINN), España., Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 1993 Optical Society of America. When this research was initiated, P. Cheben was a fellow from the Czechoslovak government-Complutense University exchange program. The authors appreciate the financial support from these institutions., We present a coupled-wave-analysis-based treatment for a wave-front conversion problem between a Gaussian beam with a cylindrical phase and a plane wave for a two-dimensional on-axis geometry. A coupled-wave approach to the multiple-scattering process in an inhomogeneous dielectric medium offers a clear physically interpretable description of the diffraction phenomena in volume media as well as the possibility of an intelligible mathematical treatment. An analytical integral solution for the amplitudes of the two modes of diffraction is submitted. High diffraction efficiency (≈1) and the deterioration of reconstruction fidelity are predicted. It is of interest to apply the model to the analysis and design of a monomode holographic fiber-to-fiber coupler, wave-front correctors, and holographic interconnection devices., Universidad Complutense de Madrid (UCM), Gobierno de Checoslovaquia, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 Optical Society of America. Financial assistance from the Spanish Ministry of Science and Technology (project TIC 2002-01846) is acknowledged. T. Alieva acknowledges the financial support of Secretaría de Estado de Educación y Universidades de España (SB2000-0166) (Spanish Ministry of Education, Culture, and Sports)., The importance of the amplitude and phase in the fractional Fourier transform (FT) domain is analyzed on the basis of the rectangular signal and the real-world image. The quality of signal restoration from only the amplitude or from only the phase of its fractional FT by applying the inverse fractional FT is considered. It is shown that the signal reconstructed from the amplitude of the fractional FT usually reveals the main features of the original signal only for relatively low fractional orders. On the basis of phase information in the fractional FT domains, significant details of the signal can be obtained for nearly all fractional orders., Ministerio de Ciencia y Tecnología, España, Secretaría de Estado de Educación y Universidades de España, Ministerio de Educación, Cultura y Deporte (MECD), España, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2011 Optical Society of America. We thank A. Cámara Iglesias for valuable discussions and advice. Financial support from the Spanish Ministry of Science and Innovation under project TEC 2008-04105 is acknowledged. P.Vaveliuk acknowledges Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil, for financial support., We propose a spectrum analyzer based on the properties of a hologram recorded with the field transmitted by a Fabry-Perot etalon. The spectral response of this holographic Fabry-Perot spectrometer (HFPS) is analytically investigated in the paraxial approximation and compared with a conventional Fabry-Perot etalon of similar characteristics. We demonstrate that the resolving power is twice increased and the free spectral range (FSR) is reduced to one-half. The proposed spectrometer could improve the operational performance of the etalon because it can exhibit high efficiency and it would be insensible to environmental conditions such as temperature and vibrations. Our analysis also extends to another variant of the HFPS based on holographic multiplexing of the transmitted field of a Fabry-Perot etalon. This device increases the FSR, keeping the same HFPS performance., Ministerio de Ciencia e Innovación, España, Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2009 Optical Society of America. The financial support of the Spanish Ministry of Science and Innovation under project TEC 2008-04105/TEC is acknowledged. T. Alieva appreciates the financial support of the Banco Santander Central Hispano and Universidad Complutense de Madrid under project Santander-Complutense, PR-34/07-15914. J. A. Rodrigo acknowledges the Spanish Ministry of Science and Innovation for the “Juan de la Cierva” grant. We also thank G. Cristóbal for his valuable discussions on the numerical calculation of the WD., We propose a simple approach for the phase space tomography reconstruction of the Wigner distribution of paraxial optical beams separable in Cartesian coordinates. It is based on the measurements of the antisymmetric fractional Fourier transform power spectra, which can be taken using a flexible optical setup consisting of four cylindrical lenses. The numerical simulations and the experimental results clearly demonstrate the feasibility of the proposed scheme., Ministerio de Ciencia e Innovación (MICINN), España, Banco Santander Central Hispano (BSCH), Universidad Complutense de Madrid (UCM), Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2007 Optical Society of America The Spanish Ministry of Education and Science is acknowledged for financial support, project TEC 2005-02180/MIC., The gyrator transform (GT) promises to be a useful tool in image processing, holography, beam characterization, mode transformation, and quantum information. We introduce what we believe to be the first flexible optical experimental setup that performs the GT for a wide range of transformation parameters. The feasibility of the proposed scheme is demonstrated on the gyrator transformation of Hermite-Gaussian modes. For certain parameters the output mode corresponds to the Laguerre-Gaussian one., Ministerio de Educación y Ciencia (MEC), España, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub

© 2006 Optical Society of America. The Spanish Ministry of Education and Science is acknowledged for financial support (Ramon y Cajal grant, T. Alieva) and projects TIC 2002-01846 and TEC 2005-02180/MIC. The authors thank Martin Bastiaans for careful reading of the manuscript and helpful discussions., On the basis of a matrix formalism, we analyze the paraxial optical systems composed by generalized lenses and fixed free-space intervals, suitable for orthosymplectic transformations in phase space. Flexible configurations to perform the attractive operations for optical information processing such as image rotation, separable fractional Fourier transformation, and twisting for different parameters are proposed., Ministerio de Educación y Ciencia (MEC), España, Depto. de Óptica, Fac. de Ciencias Físicas, TRUE, pub