Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFabrication of Hybrid Nanostructures via Nanoscale Laser-Induced Reshaping for Advanced Light Manipulation
82
0
0.0
(
0
)
Added by
Alexsandr E Krasnok
Publication date
2016
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Hybrid nanophotonics based on metal-dielectric nanostructures unifies the advantages of plasmonics and all-dielectric nanophotonics providing strong localization of light, magnetic optical response and specifically designed scattering properties. Here we demonstrate a novel approach for fabrication of ordered hybrid nanostructures via femtosecond laser melting of asymmetrical metal-dielectric (Au-Si) nanoparticles created by lithographical methods. The approach allows selective reshaping of the metal components of the hybrid nanoparticles without affecting dielectric ones. We apply the developed approach for tuning of the hybrid nanostructures scattering properties in the visible range. The experimental results are supported by molecular dynamics simulation and numerical solving of Maxwell equations.
rate research
Read More
Surface diffusion has an impact on the lateral resolution of nanostructures in bottom-up atom nanofabrication. In this paper we study the effects of the gallium atoms self-assembled on silicon surfaces (100) patterned with trenches at different slopes. These particular substrate morphologies have been made to enable an effective deposition rate variation along the surface. In this way we experimentally mimic the effect of the atomic flux modulation created by standing wave during an atom nanofabrication experiment. Even if we observe self organization of gallium atoms on the surface, we conclude that the nano-islands are not affected by surface diffusion processes and the effective variation of the deposition rate per unit area is the dominant factor affecting the growth differences along the surface. This result demonstrates that the gallium atoms self-organization should not prevent the observation of a periodic nano-patterning created by atom nano-fabrication techniques.
Nanoscale thermally assisted hydrodynamic melt perturbations induced by ultrafast laser energy deposition in noble-metal films produce irreversible nanoscale translative mass redistributions and results in formation of radially-symmetric frozen surface structures. We demonstrate that the final three-dimensional (3D) shape of the surface structures formed after resolidification of the molten part of the film is shown to be governed by incident laser fluence and, more importantly, predicted theoretically via molecular dynamics modeling. Considering the underlying physical processes associated with laser-induced energy absorption, electron-ion energy exchange, acoustic relaxation and hydrodynamic flows, the theoretical approach separating slow and fast physical processes and combining hybrid analytical two-temperature calculations, scalable molecular-dynamics simulations, and a semi-analytical thin-shell model was shown to provide accurate prediction of the final nanoscale solidified morphologies, fully consistent with direct electron-microscopy visualization of nanoscale focused ion-beam cuts of the surface structures produced at different incident laser fluences. Finally, these results are in reasonable quantitative agreement with mass distribution profiles across the surface nanostructures, provided by their noninvasive and non-destructive nanoscale characterization based on energy-dispersive x-ray fluorescence spectroscopy, operating at variable electron-beam energies.
We study experimentally and theoretically the temperature dependence of transverse magnetic routing of light emission from hybrid plasmonic-semiconductor quantum well structures where the exciton emission from the quantum well is routed into surface plasmon polaritons propagating along a nearby semiconductor-metal interface. In II-VI and III-V direct band semiconductors the magnitude of routing is governed by the circular polarization of exciton optical transitions, that is induced by a magnetic field. For structures comprising a (Cd,Mn)Te/(Cd,Mg)Te diluted magnetic semiconductor quantum well we observe a strong directionality of the emission up to 15% at low temperature of 20 K and magnetic field of 485 mT due to giant Zeeman splitting of holes mediated via the strong exchange interaction with Mn$^{2+}$ ions. For increasing temperatures towards room-temperature the magnetic susceptibility decreases and the directionality strongly decreases to 4% at T = 45 K. We also propose an alternative design based on a non-magnetic (In,Ga)As/(In,Al)As quantum well structure, suitable for higher temperatures. According to our calculations, such structure can demonstrate emission directionality up to 5% for temperatures below 200 K and moderate magnetic fields of 1 T.
We report the creation and real-space observation of magnetic structures with well-defined topological properties and a lateral size as low as about 150 nm. They are generated in a thin ferrimagnetic film by ultrashort single optical laser pulses. Thanks to their topological properties, such structures can be classified as Skyrmions of a particular type that does not require an externally applied magnetic field for stabilization. Besides Skyrmions, we are able to generate magnetic features with topological characteristics that can be tuned by changing the laser fluence. The stability of such features is accounted for by an analytical model based on the interplay between the exchange and the magnetic dipole-dipole interactions
In order to achieve polariton lasing at room temperature, a new fabrication methodology for planar microcavities is proposed: a ZnO-based microcavity in which the active region is epitaxially grown on an AlGaN/AlN/Si substrate and in which two dielectric mirrors are used. This approach allows as to simultaneously obtain a high-quality active layer together with a high photonic confinement as demonstrated through macro-, and micro-photoluminescence ({mu}-PL) and reflectivity experiments. A quality factor of 675 and a maximum PL emission at k=0 are evidenced thanks to {mu}-PL, revealing an efficient polaritonic relaxation even at low excitation power.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
