Sánchez Brea, Luis Miguel

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First Name
Luis Miguel
Last Name
Sánchez Brea
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
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Search Results

Now showing 1 - 7 of 7
  • Publication
    Stokes polarimeter using vector diffractive optical elements
    (2023-05-31) Soria García, Ángela; Del Hoyo Muñoz, Jesús; Sánchez Brea, Luis Miguel; Pastor Villarrubia, Verónica; González Fernández, Verónica; Elshorbagy, Mahmoud H.; Alda Serrano, Javier
    We 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.
  • Publication
    Calibration of the complete Jones matrix of SLMs
    (SPIE-International Society Optical Engineering, 2021-09) Hoyo Muñoz, Jesús del; Sánchez Brea, Luis Miguel; Soria García, Ángela
    Spatial light modulators are very common in many applications. They are used to implement amplitude, phase and polarization masks. In order to optimize its performance, it is important to characterize it, which means determining its Jones matrix. Here we present a method which consists on performing several intensity measurements for each gray level. It is simple enough that can be quickly performed, but offers much better results than previous methods.
  • Publication
    Femtosecond laser fabrication of LIPSS-based waveplates on metallic surfaces
    (Elsevier Science B. V., 2020-08-01) San Blas, A.; Martínez Calderón, M.; Buencuerpo Fariña, Jerónimo; Sánchez Brea, Luis Miguel; Hoyo, J. del; Gómez Aranzadi, M.; Rodriguez, A.; Olaizola, S.M.
    A fast and reliable method for the fabrication of polarization modifying devices using femtosecond laser is reported. A setup based on line focusing is used for the generation of LIPSS on stainless steel, processing at different speeds between 0.8 and 2.4 mm/s with constant energy per pulse of 1.4 mJ. SEM and AFM characterizations of the LIPSS show a progressive increase in period as the processing speed increases, while height remains approximately constant in the studied range. Optical characterization of the devices shows an induced change in the polarization of the reflected beam that varies with the processing speed, which allows a controlled fabrication of these devices.
  • Publication
    Near field diffraction of steel tape gratings illuminated with finite-size incoherent sources
    (Elsevier, 2022-02) Torcal Milla, Francisco José; Sánchez Brea, Luis Miguel
    Steel tape gratings are diffraction gratings engraved on a steel substrate, whose slits are commonly manufactured by laser ablation. They behave as amplitude diffraction gratings, since the engraved slits act as strong scatters. Here, we extend previous works to the case of finite-size illumination sources, as they are used in applications such as optical encoders, where LEDs are commonly used as illumination sources. We obtain an analytical formulation for the near field behavior of this kind of gratings. When the light source increases its size, a decreasing in the contrast of the self-images is added to the effect of the surficial roughness. The agreement between analytical and numerical results is high, validating the obtained formulation. Besides, these results could be crucial in metrological applications in which steel tape gratings or other diffractive optical elements engraved on steel substrates are used, providing with a theoretical formalism to analyze the near field propagation of light after reflecting in them.
  • Publication
    Design and numerical analysis of metallic Ronchi diffraction gratings acting as reflective beam-splitter
    (Gustav Fischer Verlag, 2022-12) Torcal Milla, Francisco José; Sánchez Brea, Luis Miguel
    In this work, a reflective beam-splitter based on a metallic Ronchi diffraction grating normally illuminated is designed and analysed. This kind of beam-splitter could have potential applications in photonics and optical technologies in which robustness is necessary since it may be manufactured over malleable metallic substrates.Methods: The main idea under the design is as simple as obligating the zero-th diffraction order to be null. Firstly, scalar approach is performed, showing an approximation to the parameters of the grating necessary to cancel zero-th diffraction order. After that, a more rigorous approach such as Rigorous Coupled Waves Analysis (TE and TM polarization) is used to evaluate the proposed diffraction gratings as reflective beam-splitters.Results: Beam-splitting is demonstrated for TE and TM polarization with slightly different dimensional parameters of the diffraction grating. Besides, we show how physical height of the grating grooves that allows cancelling zero-th diffraction order for a certain illumination wave-length depends on the metals used to manufacture the grating and its period. The dependence of the grooves height on the period is exponentially decreasing. To complete the analysis, we demonstrate how for a given grating period, the grooves height also depends on the illumination wavelength.
  • Publication
    Calibration method to determine the complete Jones matrix of SLMs, Corrigendum (vol 151, 106914, 2022)
    (Elsevier Sci. Ltd., 2023-04) Hoyo Muñoz, Jesús del; Sánchez Brea, Luis Miguel; Soria García, Ángela
  • Publication
    Sector-based Fresnel zone plate with extended depth of focus
    (Elsevier, 2022-05-24) Torcal Milla, Francisco José; Sánchez Brea, Luis Miguel; Gómez Pedrero, José Antonio
    A Sector-based Fresnel zone plate consists of a binary diffractive lens composed of a mosaic of sectors of Fresnel zone plates with different focal distances. When these focal distances are linearly distributed within the sectors, dual focus is obtained. Besides, we explore the possibility to generate an extended depth-of-focus lens by using a cubic distribution of the focal distances assigned to the sectors and optimizing the weight factors given to the terms of the cubic polynomial. Finally, numerical simulations based on the Rayleigh-Sommerfeld approach are carried out and experimental verifications by using a Spatial Light Modulator are performed, showing high agreement. The proposed kind of zone plate has potential applications in different research fields such as microscopy, lithography, data storage, or imaging.