1,721,204 research outputs found
Deterministic generation of entanglement in quantum networks by distributed coherent absorption
No full textWe demonstrate that coherent absorption offers a robust and efficient way to generate quantum entanglement in multi-nodal quantum networks. Proof-of principle experiment in a bi-nodal network is reported.</p
Black GaAs: Gold-Assisted Chemical Etching for Light Trapping and Photon Recycling
No full textThanks to its excellent semiconductor properties, like high charge carrier mobility and absorption coefficient in the near infrared spectral region, GaAs is the material of choice for thin film photovoltaic devices. Because of its high reflectivity, surface microstructuring is a viable approach to further enhance photon absorption of GaAs and improve photovoltaic performance. To this end, metal-assisted chemical etching represents a simple, low-cost, and easy to scale-up microstructuring method, particularly when compared to dry etching methods. In this work, we show that the etched GaAs (black GaAs) has exceptional light trapping properties inducing a 120 times lower surface reflectance than that of polished GaAs and that the structured surface favors photon recycling. As a proof of principle, we investigate photon reabsorption in hybrid GaAs:poly (3-hexylthiophene) heterointerfaces
A non-volatile chalcogenide switchable hyperbolic metamaterial
No full textPhase change materials have enabled the realization of dynamic nanophotonic devices with various functionalities. Reconfigurable hyperbolic metamaterials integrated with such elements have been demonstrated in the past but the volatile nature of their optical properties has been a limitation, particularly for applications that require the device to be preserved in a specified state. Here, we report the first proof-of-concept demonstration of a non-volatile, switchable hyperbolic metamaterial based on a chalcogenide glass. By using the Ge2Sb2Te5 (GST) alloy as one of the components of a multilayered nanocomposite structure and exploiting its phase change property, we demonstrate a hyperbolic metamaterial in which the type-I hyperbolic dispersion (ε⊥<0, ε∥>0) and negative refraction can be switched from the near-infrared to the visible region. This opens up new opportunities for reconfigurable device applications, such as imaging, optical data storage and sensing
Anisotropic photoluminescence properties of oriented poly(p-phenylene-vinylene) films: Effects of dispersion of optical constants
No full textWe report on the effects of dispersive optical constants on the anisotropic photoluminescence spectra of
highly oriented poly-phenylene-vinylene films. Polarized transmittance, reflectance, and photoluminescence
PL spectra have been measured over a broad spectral range, at different temperatures. Due to the high degree
of chain orientation in the polymer films, the emission properties are highly anisotropic. The PL spectral shape
and external quantum efficiency are significantly affected by self-absorption inside the polymer film and by
refractive effects at the polymer-air interface. In order to elucidate these aspects we have determined the
dispersion of the parallel and perpendicular components of the complex dielectric constant, by which
the PL spectra have been corrected according to Fresnel equations. After correction, the PL intensity is found
to be higher when the excitation is polarized perpendicular to the stretching direction, a fact that we attribute
to charge-induced PL quenching. We have also considered the influence of the refractive index on the PL
spontaneous emission rate and on the light extraction from the polymer film. The spectral dependence of the
emission anisotropy functions of the corrected PL spectra indicates the presence of two distinct emitting
species, which may originate from intramolecular and intermolecular states
Polarized optical and photoluminescence properties of highly oriented poly(p-phenylene-vinylene)
No full textWe report on the anisotropic reflectance (R), transmitlatice (T) and photoluminescence (PL) properties of stretch-oriented free standing films of poly(phenylene-vinylene) (PPV) at different temperatures. The PL quantum efficiency is strongly dependenl on the pumo polarization, being higher when pump is polarized perpendicular lo the polymer chain orientation. Independently of the pump polarization, we find that the PL emission spectra are mainly polarized along the polymer chain direction. The PL spectra have been corrected both for the number of absorbed photons and for self-absorption of the emitted light.
Frank-Condon analysis of the oscillator strengrh for absorption and corrected emission spectra suggest that two different "chromophores" contribute to the optical properties
Manipulation of single photon quantum states by coherent perfect absorption in a fiber network
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