1,721,045 research outputs found
Helical light emission from plasmonic vortices via magnetic tapered tip
Full text linkWe investigate an architecture where a plasmonic vortex excited in a gold surface propagates on an adiabatically tapered magnetic tip and detaches to the far-field while carrying a well-defined optical angular momentum. We analyze the out-coming light and show that, despite generally high losses of flat magnetic surface, our 3D structure exhibits high energy throughput. Moreover, we show that once a magneto-optical activity is activated inside the magnetic tip a modulation of the total power transmittance is possible
3D nanoporous antennas as a platform for high sensitivity IR plasmonic sensing
Full text linkNanoporous gold can be exploited as plasmonic material for enhanced spectroscopy both in the visible and in the near-infrared spectral regions. In particular, the peculiar morphology of such a substrate leads to a higher field confinement with respect to conventional plasmonic materials. This property can be exploited to achieve extremely high sensitivity to the changes in environmental conditions, making it an interesting tool for the development of sensors and biosensors. Here, we compared the sensitivity of a plasmonic resonator made of nanoporous gold with a similar structure made of homogeneous gold. To assess the enhanced sensitivity the same stoichiometric quantity of dielectric material was deposited via Atomic Layer Deposition onto the two considered structures. Experimental results proved the higher sensitivity was achievable using nanoporous gold. In particular. such 3D nanoporous structures can be proposed as a promising sensing platform in the near-infrared with a sensitivity over 4.000 nm/RIU. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen
Helicity locking of chiral light emitted from a plasmonic nanotaper
No full textSurface plasmon waves carry an intrinsic transverse spin, which is locked to its propagation direction. Apparently, when a singular plasmonic mode is guided on a conic surface this spin-locking may lead to a strong circular polarization of the far-field emission. Specifically, a plasmonic vortex excited on a flat metal surface propagates on an adiabatically tapered gold nanocone where the mode accelerates and finally beams out from the tip apex. The helicity of this beam is shown to be single-handed and stems solely from the transverse spin-locking of the helical plasmonic wave-front. We present a simple geometric model that fully predicts the emerging light spin in our system. Finally, we experimentally demonstrate the helicity-locking phenomenon by using accurately fabricated nanostructures and confirm the results with the model and numerical data
Plasmonic Nanopores for Single-Molecule Detection and Manipulation: Toward Sequencing Applications
Full text linkSolid-state nanopore-based sensors are promising platforms for next-generation sequencing technologies, featuring label-free single-molecule sensitivity, rapid detection, and low-cost manufacturing. In recent years, solid-state nanopores have been explored due to their miscellaneous fabrication methods and their use in a wide range of sensing applications. Here, we highlight a novel family of solid-state nanopores which have recently appeared, namely plasmonic nanopores. The use of plasmonic nanopores to engineer electromagnetic fields around a nanopore sensor allows for enhanced optical spectroscopies, local control over temperature, thermophoresis of molecules and ions to/from the sensor, and trapping of entities. This Mini Review offers a comprehensive understanding of the current state-of-the-art plasmonic nano pores for single-molecule detection and biomolecular sequencing applications and discusses the latest advances and future perspectives on plasmonic nano-porebased technologies
Zirconia based functional sol-gel resist for UV and high resolution lithography
No full textThe development of a functional negative tone sol-gel resist for Ultraviolet (UV) and Electron Beam (EB) lithography is presented. A new highly inorganic system based on ZrO2 is synthesized by sol-gel method. The lithographic performances have been optimized and several structures spanning from the micron range down to less than 50 nm have been achieved by UV and EB lithography. Moreover, in order to test the bio-affinity of the developed system, a genomic DNA probe has been attached onto the ZrO2 film surface. Different thermal treatments have been applied to the samples and preliminary results show different degrees of anchoring, depending on the final ZrO2 film structure (hybrid -> inorganic or amorphous -> crystalline). FT-IR characterization confirms the successful DNA functionalization of the patternable ZrO2 system, especially in the crystalline phase, opening the way to the design of new biosensor architectures. (C) 2013 Elsevier B.V. All rights reserved
Photonic Cavity Effects for Enhanced Efficiency in Layered Perovskite-Based Light-Emitting Diodes
Full text linkMagnetic control of particle trapping in a hybrid plasmonic nanopore
Full text linkpeer reviewedPlasmonic nanopores are extensively investigated as single molecules detectors. The main limitations in plasmonic nanopore technology are the too fast translocation velocity of the molecule through the pore and the consequent very short analysis times, as well as the possible instabilities due to local heating. An interesting approach to enable longer acquisition times is represented by the ability to stably trap the nanoparticles used to tag molecules close to the nanopore. Here, we theoretically investigate the performance of a magneto-plasmonic nanopore prepared with a thin layer of cobalt sandwiched between two gold layers. A nanopore is then coupled with a bifunctional (magnetic and plasmonic) core–shell nanoparticle made of magnetite (core) covered with a thin layer of gold (shell). By setting the magnetic configuration of the cobalt layer around the pore by an external magnetic field, it is possible to generate a nanoscale magnetic tweezer to trap the nanoparticle at a specific point. Considering a ∼10 nm diameter magnetite nanoparticle, we calculate a trapping force up to 28 pN, an order of magnitude above the force that can be obtained with standard optical or plasmonic trapping approaches. Moreover, the magnetic force pulls the nanoparticle in close contact with the plasmonic nanopore's wall, thus enabling the formation of a nanocavity enclosing a sub-10 nm3 confined electromagnetic field with an average field intensity enhancement up to 230 at near-infrared wavelengths. The presented hybrid magneto-plasmonic system points toward a strategy to improve nanopore-based biosensors for single-molecule detection and potentially for the analysis of various biomolecules.ULTRO
Synthesis of heteroepytaxial 3C-SiC by means of PLD
No full textThin films of silicon carbide (SiC) have been prepared by means of pulsed laser deposition (PLD) on sapphire (Al(2)O(3)) and Si(100) substrates with a Nd-YAG laser 1064 nm. We achieved the growth of cubic silicon carbide (3C-SiC) films at the temperatures of 650A degrees C from a SiC target in vacuum. The as-deposited films are morphologically and structurally characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The use of off-axis PLD method placing the sample at 90A degrees with respect to the target leads to a good quality smooth film
Detecting COVID-19 from Breath: A Game Changer for a Big Challenge
No full textCoronavirus disease 2019 (COVID-19) is probably the most commonly heard word of the last 12 months. The outbreak of this virus (SARS-CoV-2) is strongly compromising worldwide healthcare systems, social behavior, and everyone's lives. The early diagnosis of COVID-19 and isolation of positive cases has proven to be fundamental in containing the spread of the infection. Even though the polymerase chain reaction (PCR) based methods remain the gold standard for SARS-CoV-2 detection, the urgent demand for rapid and wide-scale diagnosis precipitated the development of alternative diagnostic approaches. The millions of tests performed every day worldwide are still insufficient to achieve the desired goal, that of screening the population during daily life. Probably the most appealing approach to consistently monitor COVID-19 spread is the direct detection of SARS-CoV-2 from exhaled breath. For instance, the challenging incorporation of reliable, highly sensitive, and cost-efficient detection methods in masks could represent a breakthrough in the development of portable and noninvasive point-of-care diagnosis for COVID-19. In this perspective paper, we discuss the critical technical aspects related to the application of breath analysis in the diagnosis of viral infection. We believe that, if achieved, it could represent a game-changer in containing the pandemic spread
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