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
12 results
Search Results
Now showing 1 - 10 of 12
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 Quantitative probability estimation of light-induced inactivation of SARS-CoV-2(Scientific Reports, 2024) Quintana Benito, Jaime; Alda, Irene; Alda Serrano, JavierDuring the COVID pandemic caused by the SARS-CoV-2 virus, studies have shown the efficiency of deactivating this virus via ultraviolet light. The damage mechanism is well understood: UV light disturbs the integrity of the RNA chain at those locations where specific nucleotide neighbors occur. In this contribution, we present a model to address certain gaps in the description of the interaction between UV photons and the RNA sequence for virus inactivation. We begin by exploiting the available information on the pathogen’s morphology, physical, and genomic characteristics, enabling us to estimate the average number of UV photons required to photochemically damage the virus’s RNA. To generalize our results, we have numerically generated random RNA sequences and checked that the distribution of pairs of nucleotides susceptible of damage for the SARS-CoV-2 is within the expected values for a random-generated RNA chain. After determining the average number of photons reaching the RNA for a preset level of fluence (or photon density), we applied the binomial probability distribution to evaluate the damage of nucleotide pairs in the RNA chain due to UV radiation. Our results describe this interaction in terms of the probability of damaging a single pair of nucleotides, and the number of available photons. The cumulative probability exhibits a steep sigmoidal shape, implying that a relatively small change in the number of affected pairs may trigger the inactivation of the virus. Our light-RNA interaction model quantitatively describes how the fraction of affected pairs of nucleotides in the RNA sequence depends on the probability of damaging a single pair and the number of photons impinging on it. A better understanding of the underlying inactivation mechanism would help in the design of optimum experiments and UV sanitization methods. Although this paper focuses on SARS-CoV-2, these results can be adapted for any other type of pathogen susceptible of UV damage.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 Educational resources for physics 101 instruction with health science degrees(2024) González Fernández, Verónica; González Cano, Agustín; Alda Serrano, Javier; Piedrahita Alonso, María Elena; Fernández Núñez, Sara; Díaz Herrera, Natalia; Navarrete Fernández, María Cruz; Ares, Laura; Orenes Plankova, AlexandraIn the present article, we present a comprehensive suite of educational resources and interactive exercises designed for initial Physics instruction targeted at students pursuing a Degree in Optics and Optometry. These materials have the potential to be adaptable and beneficial across various disciplines within the realm of Health Sciences. We begin by performing a preliminary analysis of the perceptions of older and new students, to develop an optimized teaching program. This consists of several workpackages aiming to increase the personal interest and involvement of the students, as well as the practical aspects regarding the subject. We include several experimental demonstrations and experiences done in the classroom. To reinforce the assimilation of most difficult concepts some educational videos are also recorded for the students.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 Geometrical limits for UV-C inactivation of pathogens(Optik, 2022) Quintana Benito, Jaime; Álvarez Fernández-Balbuena, Antonio; Martínez Antón, Juan Carlos; Vázquez Moliní, Daniel; Prada, Luis; Estrada, Luis; Alda Serrano, JavierThe inactivation of pathogens through the irradiation of ultraviolet light depends on how light propagates within the medium where the microorganism is immersed. A simple geometrical optics analysis, and a fluence evaluation reveal some reservoirs where the pathogen may hide and be weakly exposed to the incoming radiation. This geometrical hide-outs also generate a tail in the plot of the total inactivation plot vs. the incoming fluence. We have analyzed these facts using geometrical optics principles and illumination engineering computational packages. The results obtained from previous biomedical measurements involving SARS-CoV-2 have been used to evaluate the inactivation degree for an spherical geometry applicable to airborne pathogens, and for an spherical cap geometry similar to that used in biomedical experiments. The case presented here can be seen as the worst-case scenario applicable under collimated illumination.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 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.Item Spectral and thermal management of hexagonal resonant structures for flexible opto-electronic transducers(Optics and Laser Technology, 2024) Hamdy Mohamed Elshorbagy, Mahmoud; Torres Lechuga, Luis G.; González, Francisco J.; Alda Serrano, Javier; Cuadrado Conde, AlexanderEfficient on-chip optoelectronic devices in sensing and energy harvesting rely on the combination of subwavelength designs and multiphysical effects. In this contribution, we experimentally analyze and computationally model the optical performance of a hexagonal two-dimensional cluster placed over a silicon substrate and separated by a dielectric layer. Its reflectance has a dip in the long wavelength infrared band. This resonance is due to the generation of localized surface plasmons at the hexagonal surface. Our experimental results validate the multiphysics computational model which can be used to improve its performance as thermal detectors on flexible substrates. In this case, the model combines computational electromagnetism and heat transfer analysis to obtain the temperature distribution in the device. From this analysis, we have designed a thermal transducer based on a metasurface. It consists of a stacked arrangement made of a periodic hexagonal metallic array, a semiconductor ultra-thin layer, a metallic mirror, and a flexible substrate made of polyimide. The structure presented in this work behaves as a spectral selective surface with a resonant wavelength determined by the size of the hexagonal elements and the configuration of the multilayer. Our results show that this device has a time constant in the order of a few milliseconds (2.3 ms). This fast response can be useful in a wide variety of applications such as high speed thermal sensing and energy harvesting.