RESUMEN
Hybrid organic-inorganic monomode waveguides of conjugated polymers on porous silicon (PS) substrates have been fabricated. Different low refractive index PS substrates, varying from 1.46 down to 1.18 have been studied. Amplified spontaneous emission (ASE) has been observed for all the samples and the ASE threshold has been monitored as a function of the PS refractive index. A decrease in the ASE threshold is detected when the PS refractive index decreases. These results have been analysed in the frame of a four level waveguide amplifier model and the theoretical predictions are in agreement with the experimental data.
RESUMEN
The solid state thermal, one pot, efficient chemical reaction between Zn and S or Se elements in a closed reactor at 650 degrees C/60 min under their autogenic pressure in an inert atmosphere yielded luminescent ZnS and ZnSe semiconducting nanopowders (NPs). Scanning and Transmission electron microscopy measurements confirmed the size and shape of the as formed ZnS and ZnSe NPs. The wide size distributions of ZnS and ZnSe NPs are confirmed by UV-vis and TEM measurements. The crystalline wurtzite phase of ZnS and face centered cubic phase of ZnSe NPs is revealed from XRD and HR-TEM measurements. The obtained Raman scattering bands also supports the formation of pure ZnS and ZnSe phases. At room temperature, a strong visible green emission centered at approximately 525 nm is measured for ZnS, while ZnSe NPs showed a broad red emission band extending from 550 to 760 nm. The putative reaction mechanism is based on the low melting and boiling points of reactants (Zn, S and Se) under their autogenic pressure in an inert atmosphere.
RESUMEN
We report a compact light source that incorporates a semiconductor light-emitting diode, nanostructured distributed feedback (DFB) Bragg grating and spin-coated thin conjugated polymer film. With this hybrid structure, we transferred electrically generated 390 nm ultraviolet light to an organic polymer via optical pumping and out-couple green luminescence to air through a second-order DFB grating. We demonstrate the feasibility of electrically driven, hybrid, compact light-emitting devices and lasers in the visible range.
RESUMEN
Efficient transmission of light through a metal layer has become a key issue for a variety of applications including light-emitting diodes and solar cells. We report here on a novel strategy where localized and extended surface plasmons are combined to maximize the fluorescence transmission through a metallic film. We show that the dispersion of an artificial material formed by an array of metal nanoparticles coupled to a flat metal layer can be engineered to make the metal film, in a specific direction, 100% transmissive.
RESUMEN
We report the sub-wavelength patterning of the optical near-field by total internal reflection illumination of a regular array of resonant gold nano-particles. Under appropriate conditions, the in-plane coupling between Localized Surface Plasmon (LSP) fields gives rise to sub-wavelength light spots between the structures. Measurements performed with an Apertureless Scanning Near-Field Optical Microscope (ASNOM) show a good agreement with theoretical predictions based on the Green dyadic method. This concept might offer a convenient way to elaborate extended optical trap landscapes for manipulation of sub-micrometer systems.