Decay of plasmons to hot carriers has recently attracted considerable interest for fundamental studies and applications in quantum plasmonics. Although plasmon-assisted hot carriers in metals have already enabled remarkable physical and chemical phenomena, much remains to be understood to engineer devices. Here, we present an analysis of the spatio-temporal dynamics of hot electrons in an emblematic plasmonic device, the adiabatic nanofocusing surface-plasmon taper. With femtosecond-resolution measurements, we confirm the extraordinary capability of plasmonic tapers to generate hot carriers by slowing down plasmons at the taper apex. The measurements also evidence a substantial increase of the “lifetime” of the electron gas temperature at the apex. This interesting effect is interpreted as resulting from an intricate heat flow at the apex. The ability to harness the “lifetime” of hot-carrier gases with nanoscale circuits may provide a multitude of applications, such as hot-spot management, nonequilibrium hot-carrier generation, sensing, and photovoltaics.

In this Letter, we study the heat dissipated at metal surfaces by the electromagnetic field scattered by isolated subwavelength apertures in metal screens. In contrast to the common belief that the intensity of waves created by local sources should decrease with the distance from the sources, we reveal that the dissipated heat at the surface remains constant over a broad spatial interval. This behavior that occurs for noble metals at near infrared wavelengths is observed with nonintrusive thermoreflectance measurements and is explained with an analytical model, which underlines the intricate role played by quasicylindrical waves in the phenomenon. Additionally, we show that, by monitoring the phase of the quasicylindrical waves, the total heat dissipated at the metal surface can be rendered substantially smaller than the heat dissipated by the launched plasmon. This interesting property offers an alternative to amplification for overcoming the loss issue in miniaturized plasmonic devices.

Radio frequency magnetron sputtering deposition of hetero-epitaxial strontium barium niobate thin films (SrxBa1-xNb2O6).Excellent electro-optic properties of Sr x Ba 1Ϫx Nb 2 O 6 crystals ͑SBN:x͒ motivate the attempts to control the deposition of high ordered SBN thin films with the aim of optical waveguiding and processing integration. We have examined the ability of sputtering techniques to deposit stoichiometric SBN thin films. Composition analysis has enabled us to probe the mechanisms which control the target-film composition transfer and to define an experimental strategy for stoichiometry control. Epitaxial ͑001͒ SBN thin films have been obtained on MgO ͑100͒ substrates, which exhibit two in-plane orientations ͑Ϯ31°͒ mirror symmetric to the MgO cell axis.