Person: Cabrera Granado, Eduardo
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First Name
Eduardo
Last Name
Cabrera Granado
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Óptica y Optometría
Department
Óptica
Area
Optica
Identifiers
5 results
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Item Plasmon-enhanced terahertz emission in self-assembled quantum dots by femtosecond pulses(Journal of Applied Physics, 2014) Carreño Sánchez, Fernando; Antón Revilla, Miguel Ángel; Melle Hernández, Sonia; Gómez Calderón, Óscar; Cabrera Granado, Eduardo; Cox, Joel; Singh, Mahi R.; Egatz-Gómez, AnaA scheme for terahertz (THz) generation from intraband transition in a self-assembled quantum dot (QD) molecule coupled to a metallic nanoparticle (MNP) is analyzed. The QD structure is described as a three-level atom-like system using the density matrix formalism. The MNP with spherical geometry is considered in the quasistatic approximation. A femtosecond laser pulse creates a coherent superposition of two subbands in the quantum dots and produces localized surface plasmons in the nanoparticle which act back upon the QD molecule via dipole-dipole interaction. As a result, coherent THz radiation with a frequency corresponding to the interlevel spacing can be obtained, which is strongly modified by the presence of the MNP. The peak value of the terahertz signal is analyzed as a function of nanoparticle's size, the MNP to QD distance, and the area of the applied laser field. In addition, we theoretically demonstrate that the terahertz pulse generation can be effectively controlled by making use of a train of femtosecond laser pulses. We show that by a proper choice of the parameters characterizing the pulse train a huge enhancement of the terahertz signal is obtained.Item From nearly tilted waves to cavity phase solitons in broad area lasers with squeezed vacuum(Physical review letters, 2004) Gómez Calderón, Óscar; Cabrera Granado, Eduardo; Antón Revilla, Miguel Ángel; Gonzalo Fonrodona, Isabel; Carreño Sánchez, Fernando; Guerra, J. M.Phase domains and phase solitons in two-level amplifying media damped by a squeezed vacuum are predicted for the first time. Two different types of pattern formation are found depending on the relative value of the cavity detuning to the squeezed parameter: the usual one in lasers via a supercritical Hopf bifurcation and a new one via pitchfork bifurcation.Item Optical pumping of a single hole spin in a p-doped quantum dot coupled to a metallic nanoparticle(Physical review B, 2013) Antón Revilla, Miguel Ángel; Carreño Sánchez, Fernando; Melle Hernández, Sonia; Gómez Calderón, Óscar; Cabrera Granado, Eduardo; Singh, Mahi R.The preparation of quantum states with a defined spin is analyzed in a hybrid system consisting of a p-doped semiconductor quantum dot (QD) coupled to a metallic nanoparticle. The quantum dot is described as a four-level atom-like system using the density matrix formalism. The lower levels are Zeeman-split hole spin states and the upper levels correspond to positively charged excitons containing a spin-up, spin-down hole pair and a spin electron. A metallic nanoparticle with spheroidal geometry is placed in close proximity to the quantum dot, and its effects are considered in the quasistatic approximation. A linearly polarized laser field drives two of the optical transitions of the QD and produces localized surface plasmons in the nanoparticle which act back upon the QD. The frequencies of these localized plasmons are very different along the two principal axes of the nanoparticle, thus producing an anisotropic modification of the spontaneous emission rates of the allowed optical transitions which is accompanied by local-field corrections. This effect translates into a preferential acceleration of some of the optical pathways and therefore into a fast initialization of the QD by excitation with a short optical pulse. The population transfer between the lower levels of the QD and the fidelity is analyzed as a function of the nanoparticle's aspect ratio, the external magnetic field, and the Rabi frequency of the driving field. It is also shown that the main effect of the local-field corrections is a lengthening of the time elapsed to reach the steady-state. The hole spin is predicted to be successfully cooled from 5 to 0.04 K at a magnetic field of 4.6 T applied in the Voigt geometry.Item Slow light in molecular-aggregate nanofilms(Physical review letters, 2011) Cabrera Granado, Eduardo; Díaz García, Elena; Gómez Calderón, ÓscarWe study slow-light performance of molecular aggregates arranged in nanofilms by means of coherent population oscillations. The molecular cooperative behavior inside the aggregate enhances the delay of input signals in the gigahertz range in comparison with other coherent population oscillation-based devices. Moreover, the problem of residual absorption present in coherent population oscillation processes is removed. We also propose an optical switch between different delays by exploiting the optical bistability of these aggregates.Item On the generality of measuring ultrabroad-band ultrashort laser pulses with the d-scan technique using ensembles of dielectric nano- and microparticles(Optics and Laser Technology, 2024) Pérez Benito, Óscar; Cabrera Granado, Eduardo; García Martín, Susana; García González, Ester; Weigand Talavera, Rosa MaríaWe demonstrate that temporal characterization of ultrabroadband laser pulses (∼ 7 fs) through the d-scan technique can be implemented using ensembles of SHG micro and/or nanocrystals independently of their crystal size and/or composition. The experimental results have been supported by numerical simulations based on the Finite-Difference-Time-Domain (FDTD) algorithm. Both, experiment and simulations show that, in spite of the low optical quality of the samples and the unavoidable appearance of incoherent light, the technique is robust and allows to measure ultrashort laser pulses using clusters of randomly distributed and piled-up polar micro- and nanocrystals.