Person: Calvo Padilla, María Luisa
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First Name
María Luisa
Last Name
Calvo Padilla
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
Department
Area
Optica
Identifiers
134 results
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Now showing 1 - 10 of 134
Item Nonlinear Effects in the Holographic Register: an Improved Alternative to Kozma Model(Optik, 1986) Pedraza Velasco, María Lourdes de; Calvo Padilla, María LuisaItem Spatial pulse characterization in periodically segmented waveguides by using dynamic programming approach(Optics Communications, 1999) Calvo Padilla, María Luisa; Lakshminarayanan, VasudevanWe present an application of the analysis of light propagation in optical waveguides using the dynamic programming technique. We have obtained results for the transit time light pulse propagated in periodically segmented waveguides. Different semiconductor materials are considered. Certain conjectures on the behavior of the temporal pulses are made.Item Phase space tomography reconstruction of the Wigner distribution for optical beams separable in Cartesian coordinates(Journal of The Optical Society Of America A-Optics Image Science and Vision, 2009) Cámara, Alejandro; Alieva, Tatiana Krasheninnikova; Rodrigo Martín-Romo, José Augusto; Calvo Padilla, María LuisaWe 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.Item Bandpass filter implemented with blazed waveguide sidewall gratings in silicon-on-insulator(Electronics Letters, 2012) Villafranca Velasco, Aitor; Bock, Przemek J.; Cheben, Pavel; Calvo Padilla, María Luisa; Schmid, Jens H.; Lapointe, Jean; Xu, Dan-Xia; Janz, Siegfried; Delâge, AndréThe fabrication and experimental characterisation of a two-stage bandpass filter based on curved waveguide sidewall gratings is reported for the silicon-on-insulator platform. At each cascaded filtering stage, the spectral components of the input signal are dispersed by the diffraction grating formed in the sidewall of a silicon strip waveguide. Different wavelengths are focused onto different positions along the Rowland circle and the filter central wavelength is selected by a specific receiver waveguide. By using two consecutive filtering stages, both the filter passband profile and the stopband rejection ratio are substantially increased. The grating is apodised and chirped to ensure a constant effective index along the grating length to minimise phase distortions. Blazed geometry is used to maximise the diffraction efficiency to the - 1st order. The device was fabricated with electron beam lithography and reactive ion etching using a single etch step. A bandwidth of 6.2 nm was measured near 1590 nm for the fabricated filter, with a roll-off of 4 dB/nm at the passband edge, and a stopband rejection of 40 dB.Item Ultra-Compact Polarization Mode Converter Implemented in a Dual-Trench Silicon-On-Insulator Waveguide(2012 Conference on Lasers And Electro-Optics (CLEO), 2012) Villafranca Velasco, Aitor; Calvo Padilla, María Luisa; Cheben, Pavel; Ortega Moñux, Alejandro; Schmid, Jens H.; Alonso Ramos, Carlos; Molina Fernández, Íñigo; Lapointe, Jean; Vachon, Martin; Janz, Siegfried; Xu, Dan-XiaWe demonstrate an ultracompact polarization mode converter based on a silicon-on-insulator waveguide with two longitudinal subwavelength trenches. An extinction ratio of 16 dB at 1.5 μm is achieved for a device length of 10 μm.Item Advanced concepts in waveguide spectrometers(2006 3rd IEEE International Conference on Group IV Photonics, 2006) Martínez Matos, Óscar; Cheben, Pavel; Schmid, Jens H.; Bogdanov, Alexei L.; Calvo Padilla, María Luisa; Delâge, André; Densmore, Adam; Janz, Siegfried; Lamontagne, Boris; Lapointe, Jean; Post, Edith; Powell, Ian; Rodrigo Martín-Romo, José Augusto; Waldron, Phillip; Xu, Dan-XiaWe present several new concepts to extend the capabilities of arrayed waveguide grating spectrometers. Strong lateral mode confinement wavegaide structure in the focal plane is used to increase resolution, a Michelson-type AWG spectrometer can improve optical throughput or etendue, and we show that AWG dispersion can be magnified many times by modifying the waveguide group index.Item Wave-front conversion between a Gaussian beam with a cylindrical phase function and a plane wave in a monomode on-axis transmission holographic coupler(Journal of the Optical Society of America A-Optics Image Science And Vision, 1993) Cheben, Pavel; Calvo Padilla, María LuisaWe 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.Item Coupled wave analysis for a reflection dephased mixed hologram grating(Optical and Quantum Electronics, 1986) Guibelalde del Castillo, Eduardo; Calvo Padilla, María LuisaA coupled-wave analysis is given for a mixed hologram grating. The effect of spatial dephasing between the absorption and phase grating which was previously presented in transmission gratings is now developed for reflection ones. The effect is presented analytically and evaluated numerically for several cases. The analysis is motivated by the photorefractive effect in electro-optic crystals.Item m-Learning and holography: compatible techniques?(Proceedings of SPIE, 2014) Calvo Padilla, María LuisaSince the last decades, cell phones have become increasingly popular and are nowadays ubiquitous. New generations of cell phones are now equipped with text messaging, internet, and camera features. They are now making their way into the classroom. This is creating a new teaching and learning technique, the so called m-Learning (or mobile-Learning). Because of the many benefits that cell phones offer, teachers could easily use them as a teaching and learning tool. However, an additional work from the teachers for introducing their students into the m-Learning in the classroom needs to be defined and developed. As an example, optical techniques, based upon interference and diffraction phenomena, such as holography, appear to be convenient topics for m-Learning. They can be approached with simple examples and experiments within the cell phones performances and classroom accessibility. We will present some results carried out at the Faculty of Physical Sciences in UCM to obtain very simple holographic recordings via cell phones. The activities were carried out inside the course on Optical Coherence and Laser, offered to students in the fourth course of the Grade in Physical Sciences. Some open conclusions and proposals will be presented.Item Holographic Fabry-Perot spectrometer(Optics Letters, 2011) Martínez Matos, Óscar; Rodrigo Martín-Romo, José Augusto; Vaveliuk, Pablo; Calvo Padilla, María LuisaWe 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.