Sánchez Brea, Luis Miguel

Profile Picture
First Name
Luis Miguel
Last Name
Sánchez Brea
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Físicas
UCM identifierORCIDScopus Author IDWeb of Science ResearcherIDDialnet IDGoogle Scholar ID

Search Results

Now showing 1 - 6 of 6
  • Publication
    Fabrication effects in the optical performance of DOEs engraved with femtosecond lasers
    (SPIE, 2021-09-17) 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.
  • Publication
    Vector diffractive optical element as a full-Stokes analyzer
    (Elsevier, 2023-03-29) Soria García, Ángela; del Hoyo Muñóz, Jesús; Sánchez Brea, Luis Miguel; Pastor Villarubia, Verónica; González Fernández, Verónica; Elshorbagy, Mahmoud Hamdy Mohamed; Alda, Javier
    The real-time characterization of the polarization state of a light beam is of importance for a variety of applications in Optics and Photonics. We have designed a device that includes a Vector Diffractive Optical Element (VDOE) to determine the polarization state of an incident light beam. The device is able to simultaneously evaluate the four Stokes parameters of the light under analysis. The VDOE is sectorized into several Fresnel zone plates, enabling a compact arrangement and facilitating optoelectronical integration. We have also developed a procedure to remove diffractive effects and systematic errors. From the simulated results, our device is able to identify any polarization incident state with an averaged uncertainty of 0.006%. Finally, we have experimentally verified the VDOE with non-ideal polarization elements to further validate and test our proposed design. The averaged uncertainty of our experimental realization is 3.33%.
  • Publication
    Fourier series diffractive lens with extended depth of focus
    (Elsevier, 2023-04-11) Soria García, Ángela; Sánchez Brea, Luis Miguel; Hoyo Muñoz, Jesús, del; Torcal Milla, Francisco José; Gómez Pedrero, José Antonio
    Angular diffractive lenses have been proven to achieve a narrow beam waist with a long depth of focus. We generalize these type of lenses by defining the angular distribution of the focal length as a Fourier series. The Fourier coefficients of the lens are optimized, using Particle Swarm Optimization algorithm, to minimize the beam width and increase its uniformity for a given depth of focus. In order to obtain a fast simulation during the optimization process, we used Chirp Z-transform algorithm. Finally, we performed an experimental verification of the results using a Spatial Light Modulator. The Fourier series diffractive lens presents a more uniform and narrower beam than previous angular lenses, in both simulations and experiments. These results may find applications in the design of contact and intraocular lenses with extended depth of focus, laser focusing and imaging systems.
  • Publication
    Optimization of angular diffractive lenses with extended depth of focus
    (IOP Publishing, Ltd., 2020-04-02) Sánchez Brea, Luis Miguel; Torcal Milla, Francisco José; Hoyo Muñoz, Jesús del; Cuadrado Conde, Alexander; Gómez Pedrero, José Antonio
    Conventional refractive lenses concentrate the incident light at focal distance. A narrow beam waist can be achieved by increasing the lens numerical aperture, but strongly reduces the depth of focus. In this paper, we explore diffractive lenses designs, with fast angular variation of the focal distance, that produce both a narrow beam waist and a long depth of focus. We predict the focusing properties or the diffractive lenses with a simple analytical model based on an incoherent superposition of standard lenses with different focal distances. The histogram of the local focal distances is used to determine the weights in the superposition. Our model optimizes the shape of the diffractive lenses, in order to extend the depth of focus, which corresponds to the lotus lens. We verify our results with numerical simulations based on Rayleigh-Sommerfeld approach. Experimentally, we validate our analytical and numerical solutions with a Spatial Light Modulator are carried out and compared to the analytical and numerical results. We have found configurations for the lotus lens where the depth of focus is significantly incremented with only a slight increment of the focal width. For example, we increased the depth of focus from 7.6 mm to 37.2 mm while the beam waist varied from 35.0 microns to 51.6 microns for a lens with diameter D~=~4~mm, and focal distance f'~=~125~mm. These results may find applications in the design of contact and intraocular lenses with extended depth of focus, laser focus generators, and imaging applications where extended depth of focus is needed.
  • Publication
    Permeable Diffractive Optical Elements for the real-time sensing of running fluids
    (2023-05) Pastor Villarrubia, Verónica; Soria García, Ángela; Del Hoyo Muñoz, Jesús; Sánchez Brea, Luis Miguel; Alda Serrano, Javier
    The 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.
  • Publication
    Diffraction Efficiency of Reflective Metallic Gratings Operating in the THz Range
    (IEEE Xplore, 2023-09-22) 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, Tomás
    Far 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.