Carreño Sánchez, Fernando

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First Name
Last Name
Carreño Sánchez
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
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Now showing 1 - 10 of 50
  • Publication
    Dipole-dipole interaction between a quantum dot and a graphene nanodisk
    (American Physical Society, 2012-09-28) Cox, Joel; Singh, Mahi R.; Gumbs, Godfrey; Antón Revilla, Miguel Ángel; Carreño Sánchez, Fernando
    We study theoretically the dipole-dipole interaction and energy transfer in a hybrid system consisting of a quantum dot and graphene nanodisk embedded in a nonlinear photonic crystal. In our model, a probe laser field is applied to measure the energy transfer between the quantum dot and graphene nanodisk, while a control field manipulates the energy transfer process. These fields create excitons in the quantum dot and surface plasmon polaritons in the graphene nanodisk which interact via the dipole-dipole interaction. Here, the nonlinear photonic crystal acts as a tunable photonic reservoir for the quantum dot, and is used to control the energy transfer. We have found that the spectrum of power absorption in the quantum dot has two peaks due to the creation of two dressed excitons in the presence of the dipole-dipole interaction. The energy transfer rate spectrum of the graphene nanodisk also has two peaks due to the absorption of these two dressed excitons. Additionally, energy transfer between the quantum dot and the graphene nanodisk can be switched on and off by applying a pump laser to the photonic crystal or by adjusting the strength of the dipole-dipole interaction. We show that the intensity and frequencies of the peaks in the energy transfer rate spectra can be modified by changing the number of graphene monolayers in the nanodisk or the separation between the quantum dot and graphene. Our results agree with existing experiments on a qualitative basis. The principle of our system can be employed to fabricate nanobiosensors, optical nanoswitches, and energy transfer devices.
  • Publication
    Adiabatically preparing quantum dot spin states in the Voigt geometry
    (AIP, 2019-01-10) Paspalakis, Emmanuel; Economou, Sophia E.; Carreño Sánchez, Fernando
    We use mutually delayed and partially overlapping optical pulses, similar to those used in stimulated Raman adiabatic passage and its variations, for the coherent control of quantum dot spin states in the Voigt geometry. We consider the quantum dot system initially in an incoherent mixture of the two electron-spin states. We show that the application of regular delayed and partially overlapping pulses can lead to initialization. In addition, if initially delayed, partially overlapping, and simultaneously switched off pulses are applied, the initially incoherent mixture can be changed to a specifically designed coherent superposition state. We also find that due to the initial conditions of the studied quantum system, the proposed methods work for different pulse orderings.
  • Publication
    Dynamic population gratings in highly doped erbium fibers
    (OSA Publising, 2011-06-07) Melle Hernández, Sonia; Gómez Calderón, Óscar; Zhuo, Zhong C.; Antón Revilla, Miguel Ángel; Carreño Sánchez, Fernando
    The efficiency of the dynamic population gratings recorded in highly doped erbium fibers has been studied. We find that the grating response increases with optical density, although the presence of erbium ion pairs in fibers with ion density of the order of 6:3 × 1025 m−3 degrades the grating efficiency. The experimental results have been reproduced including inhomogeneous upconversion processes in the nonlinear coupled-wave equations.
  • Publication
    Optical and microwave control of resonance fluorescence and squeezing spectra in a polar molecule
    (American Physical Society, 2017-12-08) Antón Revilla, Miguel Ángel; Razavi, S. Maede; Carreño Sánchez, Fernando; Thanopulos, Ioannis; Paspalakis, Emmanuel
    A two-level quantum emitter with broken inversion symmetry simultaneously driven by an optical field and a microwave field that couples to the permanent dipole's moment is presented. We focus to a situation where the angular frequency of the microwave field is chosen such that it closely matches the Rabi frequency of the optical field, the so-called Rabi resonance condition. Using a series of unitary transformations we obtain an effective Hamiltonian in the double-dressed basis which results in easily solvable Bloch equations which allow us to derive analytical expressions for the spectrum of the scattered photons. We analyze the steady-state population inversion of the system which shows a distinctive behavior at the Rabi resonance with regard to an ordinary two-level nonpolar system. We show that saturation can be produced even in the case that the optical field is far detuned from the transition frequency, and we demonstrate that this behavior can be controlled through the intensity and the angular frequency of the microwave field. The spectral properties of the scattered photons are analyzed and manifest the emergence of a series of Mollow-like triplets which may be spectrally broadened or narrowed for proper values of the amplitude and/or frequency of the low-frequency field. We also analyze the phase-dependent spectrum which reveals that a significant enhancement or suppression of the squeezing at certain sidebands can be produced. These quantum phenomena are illustrated in a recently synthesized molecular complex with high nonlinear optical response although they can also occur in other quantum systems with broken inversion symmetry.
  • Publication
    Líneas de investigación del Grupo UCM de Física del Láser, Óptica Cuántica y Óptica No Lineal
    (Sociedad Española de óptica, 2011) Antón Revilla, Miguel Ángel; Arrieta Yáñez, Francisco; Cabrera Granado, Eduardo; Carreño Sánchez, Fernando; Ezquerro Rodríguez, José Miguel; Gómez Calderón, Óscar; Gonzalo Fonrodona, Isabel; Guerra Pérez, José Manuel; Melle Hernández, Sonia; Soler Rus, Miguel Odín; Sánchez Balmaseda, Margarita María; Weigand Talavera, Rosa María
    En este trabajo presentamos las líneas de investigación del Grupo de Física del Láser, Óptica Cuántica y Óptica No Lineal de la UCM. La investigación comprende trabajos experimentales y teóricos en el desarrollo de prototipos de láser, análisis de inestabilidades espacio-temporales en láseres de gran apertura, el estudio de propagación de radiación en régimen de luz lenta y de pulsos ultracortos en medios resonantes y no resonantes, la generación de radiación por procesos no lineales y el estudio de memorias ópticas por eco fotónico.
  • Publication
    Absorption of a weak probe in singly charged n-doped quantum dots in the Voigt geometry
    (IOP Publishing, 2019-01-04) Carreño Sánchez, Fernando; Antón Revilla, Miguel Ángel
    We analyze the absorption of a weak probe field in singly charged n-doped quantum dots in the presence of an external magnetic field in the Voigt geometry. The dots are modeled as double lambda systems. A laser field pumps two of the four active transitions while a probe field is applied along the two undriven transitions. It is shown that for both on resonance and out of resonance driving gain (without inversion) is obtained at two sidebands of the dressed QDs. We found that the peak value of gain can be maximized by a proper selection of both the external magnetic field and the Rabi frequency of the pump field for out of resonance driving. We also show that the coherent driving in combination with above-band excitation allows one to turn the absorption peaks into gain (with inversion) in the whole spectral range.
  • Publication
    The use of metamers to compare the color vision of observers
    (John Wiley & Sons, Inc., 2001-08) Ezquerro Rodríguez, José Miguel; Carreño Sánchez, Fernando; Zoido Chamorro, Jesús Manuel; Bernabeu Martínez, Eusebio
    In this research we compare the colorimetric behavior of several observers. For color centers recommended by CIE we have produced large sets of spectral distributions, which are metameric for the CIE 1931 standard observer. For each one of the color centers, we compare the clouds of chromaticity coordinates with the chromaticity thresholds. We define a parameter that provides a quantitative measure of the interobserver variability. This parameter is used to arrange the observers by their degree of likeness. A similar procedure has been used to compare two real observers. It is shown how there is no reciprocity between the colorimetric behavior of two real observers
  • Publication
    Plasmonic control of nonlinear two-photon absorption in graphene nanocomposites
    (IOP Publishing Ltd., 2013-08-29) Cox, Joel D.; Singh, Mahi R.; Antón Revilla, Miguel Ángel; Carreño Sánchez, Fernando
    Nonlinear two-photon absorption in a quantum dot–graphene nanoflake nanocomposite system has been investigated. An external laser field is applied to the nanocomposite to simultaneously observe two-photon processes in the quantum dot and excite localized surface plasmons in the graphene nanodisk. This resonance condition can be achieved by tuning the plasmon resonance frequency in the graphene nanoflake via electrostatic gating. It is found that the strong local field of the graphene plasmons can enhance and control nonlinear optical processes in the quantum dot. Specifically, we show that the two-photon absorption coefficient in the quantum dot can be switched between single- and double-peaked spectra by modifying the graphene–quantum dot separation. Two-photon processes in the quantum dot can also be switched on or off by slightly changing the gate voltage applied to the graphene. Our findings indicate that this system can be used for nonlinear optical applications such as all-optical switching, biosensing and signal processing.
  • Publication
    The Weber fraction and asymmetries in luminance thresholds
    (John Wiley & Sons, Inc., 2002-10) Carreño Sánchez, Fernando; Zoido Chamorro, Jesús Manuel
    Presented in this article is a method for the determination of the Weber fraction by analyzing data obtained from color-matching experiments. The method is based on a rigorous analysis of the probability density function derived from discrimination judgments made in the xyY space. Analysis shows the thresholds for luminance increments and decrements are shown to be different and asymmetric and the Weber fraction to depend on the target's level of luminance and chromaticity.
  • Publication
    Plasmonic effects in excitonic population transfer in a driven semiconductor–metal nanoparticle hybrid system
    (American Physical Society, 2012) Antón Revilla, Miguel Ángel; Carreño Sánchez, Fernando; Melle Hernández, Sonia; Calderón, Oscar Gómez; Cabrera Granado, Eduardo; Cox, Joel; Singh, Mahi R.
    We have investigated the coherent transfer of excitonic populations in a semiconductor quantum dot (SQD) modulated by the surface plasmon of a metallic nanoparticle (MNP). The SQD is considered as a three-level V-type atomic system. We applied a transform-limited laser pulse field resonant with the upper atomic levels of the SQD. When the SQD is close enough to the MNP, the otherwise equally populated atomic levels can be selectively excited. Selectivity population can be achieved by two physical mechanisms: an enhancement of the Rabi frequencies that drive the optical transitions, which depends on the polarization arrangement, and a frequency shift of the optical transitions that leads to a dynamical detuning.