Person:
Martínez Antón, Juan Carlos

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First Name
Juan Carlos
Last Name
Martínez Antón
URI
https://hdl.handle.net/20.500.14352/79892
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Óptica
Area
Optica
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2015 - 201932020 - 20211
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Now showing 1 - 4 of 4
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    Resonant elements contactless coupled to bolometric micro-stripes
    (Proceedings of SPIE, 2015) Cuadrado, Alexander; Silva-López, Manuel; López-Alonso, José Manuel; Martínez Antón, Juan Carlos; Ezquerro Rodríguez, José Miguel; González, Francisco Javier; Alda, Javier
    One of the main technical difficulties in the fabrication of optical antennas working as light detectors is the proper design and manufacture of auxiliary elements as load lines and signal extraction structures. These elements need to be quite small to reach the location of the antennas and should have a minimal effect on the response of the device. Unfortunately this is not an easy task and signal extraction lines resonate along with the antenna producing a complex signal that usually masks the one given by the antenna. In order to decouple the resonance from the transduction we present in this contribution a parametric analysis of the response of a bolometric stripe that is surrounded by resonant dipoles with different geometries and orientations. We have checked that these elements should provide a signal proportional to the polarization state of the incoming light.
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    Measuring the absorption coefficient of optical materials with arbitrary shape or distribution within an integrating sphere
    (Optics Express, 2021) Martínez Antón, Juan Carlos; Gómez Manzanares, Ángela; Álvarez Fernández-Balbuena, Antonio; Vázquez Moliní, Daniel
    The absorption coefficient of a material is classically determined by measuring the transmittance of a homogeneous sample contained within flat optical faces and under collimated illumination. For arbitrary shapes this method is impracticable. The characterization of inhomogeneous or randomly distributed samples such as granules, powders or fibers suffers the same problem. Alternatively, an integrating cavity permits us to illuminate a sample under a homogenous and isotropic light field where the analysis simplifies. We revisit this strategy and present a new formal basis based on simple radiometric laws and principles. We introduce a new concept to describe the absorption: the optical form factor. We tackle a rigorous treatment of several regular forms, including full absorption range and the reflection at its surfaces. We also model and improve an integrating sphere setup to perform reliable measurements. Altogether, it permits achieving simple but general conclusions for samples with arbitrary shape or spatial distribution, from weak to highly absorbing, expanding the applicability of quantitative absorption spectroscopy. Finally, we validate it by measuring different sample formats made of PMMA: a cube, groups of granules and injection molding loose parts. The absorption coefficient of PMMA varies near three orders of magnitude in the explored range (380-1650 nm).
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    Detectivity comparison of bolometric optical antennas
    (Proceedings of SPIE, 2015) Cuadrado, Alexander; López-Alonso, José Manuel; Martínez Antón, Juan Carlos; Ezquerro Rodríguez, José Miguel; González, Francisco Javier; Alda, Javier
    The practical application of optical antennas in detection devices strongly depends on its ability to produce an acceptable signal-to-noise ratio for the given task. It is known that, due to the intrinsic problems arising from its sub-wavelength dimensions, optical antennas produce very small signals. The quality of these signals depends on the involved transduction mechanism. The contribution of different types of noise should be adapted to the transducer and to the signal extraction regime. Once noise is evaluated and measured, the specific detectivity, D*, becomes the parameter of interest when comparing the performance of antenna coupled devices with other detectors. However, this parameter involves some magnitudes that can be defined in several ways for optical antennas. In this contribution we are interested in the evaluation and comparison of D_ values for several bolometric optical antennas working in the infrared and involving two materials. At the same time, some material and geometrical parameters involved in the definition of noise and detectivity will be discussed to analyze the suitability of D_ to properly account for the performance of optical antennas.
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    Analysis of the spectral response of fractal antennas related with its geometry and current paths
    (Proceedings of SPIE, 2015) Cuadrado, Alexander; López-Alonso, José Manuel; Martínez Antón, Juan Carlos; Ezquerro Rodríguez, José Miguel; González, Francisco Javier; Alda, Javier
    Fractal antennas have been proposed to improve the bandwidth of resonant structures and optical antennas. Their multiband characteristics are of interest in radiofrequency and microwave technologies. In this contribution we link the geometry of the current paths built-in the fractal antenna with the spectral response. We have seen that the actual currents owing through the structure are not limited to the portion of the fractal that should be geometrically linked with the signal. This fact strongly depends on the design of the fractal and how the different scales are arranged within the antenna. Some ideas involving materials that could actively respond to the incoming radiation could be of help to spectrally select the response of the multiband design.