We report on the fabrication and optical characterization of hyperbolic nanoparticles on a transparent substrate. These nanoparticles enable a separation of ohmic and radiative channels in the visible and near-infrared frequency ranges. The presented architecture opens the pathway towards novel routes to exploit the light to energy conversion channels beyond what is offered by current plasmon-based nanostructures, possibly enabling applications spanning from thermal emission manipulation, theragnostic nano-devices, optical trapping and nano-manipulation, non-linear optical properties, plasmonenhanced molecular spectroscopy, photovoltaics and solar-water treatments, as well as heat-assisted ultra-dense and ultrafast magnetic recording.
We fabricated hollow nanoantennas with varying inner channels sizes on a gold-covered silicon nitride membrane. Our fabrication technique allowed us to narrow the size of the inner channels down to 15nm. We managed to exclusively decorate the tips of the antennas with thiol-conjugated dyes by creating a concentration gradient through the nanoantennas. Finally, we characterized the antennas in terms of their effect on the lifetime of dyes. We used Atto 520 and Atto 590 for the experiments. We carried out experiments with the antennas decorated with Atto 520, with Atto 590 as well as with the two Atto dyes at the same time. The experiments carried out with the antennas decorated with Atto 520 only and Atto 590 only yielded a lifetime reduction with respect to the confocal case. Interestingly, their lifetime reductions were significantly different. Then, we decorated the antennas with the two dyes at the same time. Even though we could not control the distance between the two dyes, FRET effects were clearly observed. The FRET effects were found to be dependent on the size of the inner channel. We believe that our tip decorated hollow nanoantennas could find application in FRET-based single molecule nanopore technologies.
Here, we propose easy and robust strategies for the versatile integration 2D material flakes on plasmonic nanoholes by means of site selective deposition of MoS2. The methods can be applied both to simple metallic flat nanostructures and to complex 3D metallic structures comprising nanoholes. The deposition methods allow the decoration of large ordered arrays of plasmonic structures with single or few layers of MoS2. We show that the plasmonic field generated by the nanohole can interact significantly with the 2D layer, thus representing an ideal system for hybrid 2DMaterial/ Plasmonic investigation. The controlled/ordered integration of 2D materials on plasmonic nanostructures opens a pathway towards new investigation of the following: enhanced light emission; strong coupling from plasmonic hybrid structures; hot electron generation; and sensors in general based on 2D materials.
A major challenge facing plasmon nanophotonics is the poor dynamic tunability. A functional nanophotonic element would feature the real-time sizeable tunability of transmission, reflection of light’s intensity or polarization over a broad range of wavelengths, and would be robust and easy to integrate. Here we devise an ultra-thin chiroptical surface, built on 2D nanoantennas, where the chiral light transmission is controlled by the externally applied magnetic field. We produced a class of highly tunable by the magnetic field macroscale bottom-up plasmonic chiroptical surfaces. The tuned parameter is the chiroptical transmission, enabled by the nanoantenna design that accommodates ferromagnetic plasmonic elements. The already significant chiroptical response of this system is further tuned up to 150% by the external magnetic field. The presented compact 2D design promises the easy integration and potentially fast operation in the broad spectral range, enabling this type of functional plasmonic surfaces entering the realm of practical optical devices. The magnetic field-induced modulation of the far-field chiroptical response with this surface exceeds 100% in the visible and near-infrared spectral ranges, opening the route for nanometer-thin magnetoplasmonic light-modulating surfaces tuned in real time and featuring a broad spectral response. For this we design a 2D composite trimer nanoantennas comprising three near-field-coupled nanosized disks of diameters close to 100 nm and identical height of 30 nm, of which one is made of a ferromagnetic material and the other two are made of a noble metal. The use of two materials breaks the 2D rotational symmetry, endowing the handedness to the trimer that results in a chiroptical response in otherwise structurally symmetric nanoantenna. We leverage on the presence of the plasmon resonances in metallic nanoferromagnets to add the magnetoplasmonic functionality to the system.
Nanoporous gold is a very promising material platform for several plasmonic applications. Nanoporous gold can be
formed by dealloying Au–Ag alloys, previously grown by means of Ag-Au co-sputtering. The optical response is
completely determined by the nanostructured film features, that only depend on the initial alloy composition. It has been
extensively used as SERS substrate both as thin film and nanofabricated fancy designs. Here we explore the potential
application of nanoporous gold as SERS substrate as it is coupled and decorated with Ag nanoparticles. Significant
enhancement has been observed in comparison with bare nanoporous film.