Plasmonic nanoparticles offer a broad range of functionalities, owing to their ability to amplify light in the near-field or convert it into heat. However, their ultrafast nonlinear optical response remains too low to envisage all-optical high-rate photonic processing applications. Here, we tackle this challenge by coupling the localized plasmon mode in gold nanoparticles with a localized photonic mode in a 1D resonant cavity. Despite the nonradiative losses, we demonstrate that a strong, reversible, and ultrafast optical modulation can be achieved. By using a light pumping fluence of less than 1 mJ cm(-2), a change of signal transmittance of more than 100% is generated within a few picosecond time scale. The nanoparticle transient optical response is enhanced by a factor of 30 to 40 while its spectral profile is strongly sharpened. The large nonlinear response of such plasmonic cavities could open new opportunities for ultrafast light processing at the nanoscale.

Abstract:In this work we present, for the first time to our knowledge, laser emission under wavelength selective laser-pulsed pumping in Nd 3+ -doped TeO 2 -ZnO-ZnF 2 bulk glass for two different Nd 3+ concentrations. The fluorescence properties of Nd 3+ ions in this matrix which include, JuddOfelt calculation, stimulated emission cross-section of the laser transition and lifetimes are also presented. The site-selective emission and excitation spectra along the 4 I 9/2 → 4 F 3/2 absorption band show the inhomogeneous behaviour of the crystal field felt by Nd 3+ ions in this fluorotellurite glass which allows for spectral tuning of the laser output pulse as a function of the pumping wavelength. The emission cross-section obtained from the Judd-Ofelt analysis and spectral data (4.9x10 −20 cm 2 ) is in fairly good agreement with the value obtained from the analysis of the laser threshold data (4x10 −20 cm 2 ).

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Transparent oxyfluoride tellurite thin film glasses have been produced at room temperature by pulsed laser deposition in O 2 atmosphere from an Er-doped TeO 2 -ZnOZnF 2 bulk glass. Thin film glasses present high refractive index (n≥ 1.95) and good transparency (T≥ 80%) in the visible (λ> 400nm) and near infrared range. However, their photoluminescence (PL) performance at 1.5 µm is poor. Thermal annealing at moderate temperatures (T≤ 315 ºC), well below glass crystallization, increases the PL 2 intensity by more than one order of magnitude as well as the PL lifetime up to τ≈ 3.3 ms. Film glasses present a larger fraction of TeO 3 trigonal pyramids than the bulk glass and a very large OH -content. The structure and composition of film glasses does not change upon annealing and thus the activation of the PL response is related to the improvement of the surface morphology and the significant decrease of their OHcontent.

a b s t r a c tNanostructured thin film glasses with a controlled concentration and in-depth distribution of Er 3+ have been produced by alternate pulsed laser deposition (PLD) from host (PbO-Nb 2 O 5 -GeO 2 ) and dopant (Er) targets (in-situ doping). Their photoluminescence (PL) response is compared to that of doped films grown by standard PLD using Er 3+ -doped glass targets (ex-situ doping), by studying the characteristic Er 3+ emission at 1.53 lm. PL intensity of in-situ doped films is maximized for in-depth separation between Erdoped layers P5 nm, whereas their lifetime is always longer in the case of nanostructured films having a separation between Er 3+ ions similar to that of ex-situ doped films. These results stem from the different distribution of Er 3+ ions in the host glass: isotropic 3D for ex-situ doped films or planar 2D for nanostructured films. Thus, the number of neighbor Er 3+ ions is larger in the first case, which favors the increase of nonradiative deexcitation due to concentration quenching.

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