Person: Alda Serrano, Javier
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First Name
Javier
Last Name
Alda Serrano
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Óptica
Area
Optica
Identifiers
8 results
Search Results
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Item Gold-coated split laser-induced periodic surface structures as refractometric sensors(Optics and Laser Technology, 2022) San Blas, Alejandro; Elshorbagy, Mahmoud Hamdy Mohamed; Olaizola Izquierdo, Santiago M.; Sánchez Brea, Luis Miguel; Rodríguez González, Ainara; Del Hoyo Muñoz, Jesús; Granados, Eduardo; Soria García, Ángela; Pastor Villarrubia, Verónica; Alda Serrano, JavierThe generation of surface plasmon resonances (SPR) in laser-induced periodic surface structures (LIPSS) allows their application in the field of optical sensing, such as the detection of refractive index variations in gases and liquids. We have fabricated gold-coated LIPSS nanostructures on stainless steel substrates by using femtosecond laser nano-ablation. This technique is a low-cost and high-throughput fabrication method applicable to fast and large-scale manufacturing. The depth profile of the fabricated LIPSS shows a central dip at the top of each ripple that split the geometry. The actual topography is modeled and included in a computational electromagnetism package to obtain the expected optical response under the experimental conditions. The measured and simulated spectral reflectances are compared, and the differences are explained by the departure of the fabricated LIPSS from the ideal topography. The experiments and simulations showed excellent agreement for the main spectral characteristics, like the Fano-like lineshapes of the spectral reflectance. This fitting provides the values used to determine the refractometric performance of the fabricated device, that shows a sensitivity of 518 nm/RIU and a figure of merit of 32 RIU−1 for an aqueous analyte. Our experimental results show that the fabricated devices are competitive in terms of cost and simplicity when compared to existing devices with similar performance.Item Stokes polarimeter using vector diffractive optical elements(2023) Soria García, Ángela; Del Hoyo Muñoz, Jesús; Sánchez Brea, Luis Miguel; Pastor Villarrubia, Verónica; González Fernández, Verónica; Elshorbagy, Mahmoud H.; Alda Serrano, JavierWe designed, fabricated and tested a Vector Diffractive Optical Element (VDOE) to simultaneously determine the Stokes vector of light. It comprises several sectors. Each one is a vector Fresnel zone plate which focuses the light on separate foci and has different polarization properties. The polarization state is calculated from their intensities. From simulations, we could identify the error sources that were analytically removed. The residual uncertainty after applying our corrections was as low as 6x10^(-5). The uncertainty obtained for our fabricated VDOE, 3.33 %, is competitive with the results from state-of-the-art techniques.Item Fabrication effects in the optical performance of DOEs engraved with femtosecond lasers(Proceedings of SPIE, 2021) Soria García, Ángela; Fantova, Jorge; San Blas, Alejandro; Hoyo Muñoz, Jesús del; Sánchez Brea, Luis Miguel; Alda Serrano, Javier; Rodríguez González, Ainara; Olaizola Izquierdo, Santiago M.The development of DOEs fabrication techniques is continuously growing due to the wide range of industrial applications, such as beam manipulation or optical position encoders. In this work, we use Femtosecond laser direct writing to manufacture DOEs, which uses a simpler and more efficient way to fabricate amplitude binary masks. Also, we have analyzed the performance of the DOEs. The fabrication technique is validated since the experimental results are in accordance to numerical simulations.Item Permeable Diffractive Optical Elements for the real-time sensing of running fluids(2023) Pastor Villarrubia, Verónica; Soria García, Ángela; Del Hoyo Muñoz, Jesús; Sánchez Brea, Luis Miguel; Alda Serrano, JavierThe real-time monitoring of physical and chemical parameters in running fluids is of importance for biomedical, biochemical, and environmental applications, such as the presence of biomarkers or chemomarkers, or the departure from some preset values of critical parameters. In this contribution we present a new generation of Permeable Diffractive Optical Elements (PDOE) based on photon sieves. In brief, the PDOE is made of passing holes properly placed on specific locations on a rigid surface. This arrangement makes PDOEs ideal to work with running fluids. Our PDOE is optimized maximizing the irradiance at is focal plane, maintaining an appropriate permeability ratio. The starting point is the classical Fresnel zone distribution. We have used two different optimization strategies to design a working PDOE: i) Particle Swarm Optimization has been applied to modify the distribution of holes on the PDOE simultaneously considering all of them; ii) an iterative minimization algorithm adding one hole at the time until filling the PDOE aperture. Both optimization algorithms generate focal spots that are compared to choose the design better suited for the proposed application. Once the PDOE is optimized and fabricated, the surface of the remaining rigid structure is nanostructured (for example using Laser Induced Periodic Surface Structures), or functionalized, to provide specific sensing capabilities. In addition, the PDOE is integrated within a pipe where the fluid under analysis circulates through. A proposal for the optoelectronic assembly of the device-including auxiliary optical elements, light sources, and detectors - is also presented in this contribution.Item Diffraction Efficiency of Reflective Metallic Gratings Operating in the THz Range(IEEE Transactions on Terahertz Science and Technology, 2023) Cuadrado Conde, Alexander; Fernández Rodríguez, M; Sánchez Brea, Luis Miguel; García Lozano, Gonzalo; Mercant, Guillermo; Torquemada ,Mº Carmen; Alda Serrano, Javier; Gonzalez , Luis M.; Belenguer Dávila, TomásFar infrared spectrometers have a prominent role to play in future space missions devoted to unveiling the obscure universe. Diffraction gratings are the heart of these instruments that, when operating in the range of a few THz, shall cover a wide spectral range providing the highest resolution and efficiency, generally for only a single polarization, within the specified spectral range. This contribution describes the optimization of the diffraction efficiency of the first diffractive order for a blazed metallic grating working at a large angle of incidence. Since the grating period is of the same order of magnitude as the wavelength, it is necessary to approach the design by solving Maxwell's equations rigorously using computational electromagnetism. We have applied the Rigorous Coupled-Wave Analysis and the Finite Element Methods to simulate the performance of the grating. This analysis provides relevant hints for the selection of the period, and the blaze and slant angles of the grating. A metallic blazed grating has been fabricated on aluminum and its topography has been characterized to determine the discrepancies with respect to the nominal values. The fabricated profile has been simulated to obtain the expected results in efficiency in comparison with the ideal case. This analysis provides guidance for improved manufacturing processes and experimental verification.Item Diffractive optical elements with square concentric rings of equal width(Microwave and Optical Technology Letters, 2010) Alda Serrano, Javier; Sánchez Brea, Luis Miguel; Salgado Remacha, Francisco Javier; Rico García, José MaríaA diffractive optical element having equal-width concentric square rings is analyzed in this article. This constant width makes possible its realization using spatial light modulators or square pixels phase screens. It allows a simple analytical treatment, and the element is also simulated using the Rayleigh-Sommerfeld approach. An experimental verification of its performance has been compared with the simulated results.Item Optimal phase distributions for polygonal Fresnel lenses(Proceedings of the Fourth European Conference on Antennas and Propagation, 2010) Alda Serrano, Javier; Salgado Remacha, Francisco Javier; Sánchez Brea, Luis Miguel; Rico García, José María; González, Francisco JavierPolygonal Fresnel zone plates can be configured in a variety of forms depending on the number of sides of the polygon and the number of phase steps used. This contribution deals with some specific polygonal designs that tessellate the plane: triangles, squares, and hexagons. The phase distribution is chosen as a continuous one to form a polygonal kinoform. The selected designs have been simulated and its behaviour compared. Although their performance is worse than the circular Fresnel plate, they may present some other advantages as the tessellation capability, and the possibility to fabricate them as extruded profiles.Item Interferometric method for simultaneous characterization of retardance and fast axis of a retarder(Optics and Lasers in Engineering, 2024) Del Hoyo Muñoz, Jesús; Porras, Joaquin Andres; Soria García, Ángela; Sánchez Brea, Luis Miguel; Pastor Villarrubia, Veronica; Hamdy Mohamed Elshorbagy, Mahmoud; Alda Serrano, JavierIn this work, we propose a technique to simultaneously measure the absolute retardance and the fast axis azimuth of a retarder using a Michelson interferometer with polarization control. One of the mirrors is slightly tilted to obtain interference fringes with collimated beams. The sample to measure is rotated and the parameters are obtained from the fringes displacement. The technique does not require the use of additional previously characterized retarders in the measurement process, but only linear polarizers. The experimental results present errors of the order of 2◦ for the retardance and 1◦ for the azimuth of the fast axis.