An interdisciplinary research team at the University of Illinois has developed a novel, tunable nanoantenna that paves the way for new kinds of plasmonic-based optomechanical systems whereby plasmonic field enhancement can actuate mechanical motion.
“Recently, there has been a lot of interest in fabricating metal-based nanotextured surfaces that are pre-programmed to alter the properties of light in a specific way after incoming light interacts with it,” explained Kimani Toussaint, an associate professor of mechanical science and engineering who led the research.
“For our approach, one can take a nanoarray structure that was already fabricated and further reconfigure the plasmonic, and hence, optical properties of select antennas. Therefore, one can decide after fabrication, rather than before, how they want their nanostructure to modify light.”
The researchers developed a novel, metal, pillar-bowtie nanoantenna (p-BNA) array template on 500-nanometer tall glass pillars (or posts). In doing so, they demonstrated that the gap size for either individual or multiple p-BNAs can be tuned down to approximately 5 nm (approx. 4x smaller than what is currently achievable using conventional electron-beam lithography techniques).
“On a fundamental level, our work demonstrates electron-beam based manipulation of nanoparticles an order of magnitude larger than previously possible, using a simple SEM operating at only a fraction of the electron energies of previous work,” said Brian Roxworthy, who earned his PhD in electrical and computer engineering (ECE) at Illinois and was first author of the paper published in Nature Communications.
“The dramatic deformation of the nanoantennas we observe is facilitated by strong in-gap plasmonic modes excited by the passing electrons, which give rise to nanoNewton-magnitude gradient forces on the constituent metal particles.”
The interdisiciplinary research team--that included Abdul Bhuiya (MS student in ECE student), Xin Yu (ECE post-grad), and K.C. Chow (a research engineer at the Micro and Nanotechnology Laboratory)—also demonstrated that a standard scanning electron microscope (SEM) can be used to deform either individual p-BNA structures or groups of p-BNAs within a sub-array with velocities as large as 60 nanometers per second. A photonic-crystal fiber was used to generate (quasi-white light) supercontinuum to probe the spectral response of select regions within the array.
The researchers said the importance of this work is three-fold: It enables tuning of the optical (plasmonic) response of the nanoantennas, down to the level of a single nanoantenna (approximately 250 nanometers across); it could lead to unique, spatially addressable nanophotonic devices for sensing and particle manipulation, for example; and, it provides a fertile platform for studying mechanical, electromagnetic, and thermal phenomena in a nanoscale system.
The team believes that the relatively high aspect ratio (pillar height-to-thickness) of 4.2 for the p-BNAs, along with a significant thermal contribution, permit sufficient compliance of the pillars to be actuated by electron-beam-induced gradient forces.
“Our fabrication process shows for the first time an innovative way of fabricating plasmonic nanoantenna structures under the SEM, which avoids complications such as proximity effects from conventional lithography techniques,” Bhuiya said. “This process also reduces the gap of the nanoantennas down to ~5 nm under SEM with a controlled reduction rate. With this new fabrication technique, it opens an avenue to study different phenomena which leads to new exciting research fields.”
Kimani Toussaint | Eurek Alert!
New dental implant with built-in reservoir reduces risk of infections
18.01.2017 | KU Leuven
Many muons: Imaging the underground with help from the cosmos
19.12.2016 | DOE/Pacific Northwest National Laboratory
For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.
According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
23.01.2017 | Health and Medicine
23.01.2017 | Physics and Astronomy
23.01.2017 | Process Engineering