Metasurface Consisting of a Rectangular Array of Rectangular Gold Nanostructures

An artist’s view of a metasurface consisting of an oblong array of rectangular gold nanostructures producing plasmonic floor lattice resonances. Credit score: Yaryna Mamchur, co-author and Mitacs Summer time Pupil from the Nationwide Technical College of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute,” who labored in Professor Ksenia Dolgaleva’s lab in the summertime of 2019 at uOttawa.

Researchers on the College of Ottawa have debunked the decade-old delusion of metals being ineffective in photonics – the science and expertise of sunshine – with their findings, not too long ago printed in Nature Communications, anticipated to result in many purposes within the discipline of nanophotonics.

“We broke the document for the resonance high quality issue (Q-factor) of a periodic array of metallic nanoparticles by one order of magnitude in comparison with earlier stories,” mentioned senior creator Dr. Ksenia Dolgaleva, Canada Analysis Chair in Built-in Photonics (Tier 2) and Affiliate Professor within the Faculty of Electrical Engineering and Laptop Science (EECS) on the College of Ottawa.

“It’s a well-known incontrovertible fact that metals are very lossy after they work together with mild, which implies they trigger the dissipation {of electrical} vitality. The excessive losses compromise their use in optics and photonics. We demonstrated ultra-high-Q resonances in a metasurface (an artificially structured floor) comprised of an array of metallic nanoparticles embedded inside a flat glass substrate. These resonances can be utilized for environment friendly mild manipulating and enhanced light-matter interplay, exhibiting metals are helpful in photonics.”

“In earlier works, researchers tried to mitigate the hostile impact of losses to entry favorable properties of metallic nanoparticle arrays,” noticed the co-lead creator of the examine Md Saad Bin-Alam, a uOttawa doctoral pupil in EECS.

“Nevertheless, their makes an attempt didn’t present a major enchancment within the high quality components of the resonances of the arrays. We applied a mixture of methods quite than a single strategy and obtained an order-of-magnitude enchancment demonstrating a metallic nanoparticle array (metasurface) with a record-high high quality issue.”

Based on the researchers, structured surfaces – additionally referred to as metasurfaces – have very promising prospects in a range of nanophotonic purposes that can by no means be explored utilizing conventional pure bulk supplies. Sensors, nanolasers, mild beam shaping and steering are only a few examples of the various purposes.

“Metasurfaces manufactured from noble metallic nanoparticles – gold or silver for example – possess some distinctive advantages over non-metallic nanoparticles. They can confine and management mild in a nanoscale quantity that is lower than one quarter of the wavelength of sunshine (lower than 100 nm, whereas the width of a hair is over 10 000 nm),” defined Md Saad Bin-Alam.

“Apparently, not like in non-metallic nanoparticles, the sunshine shouldn’t be confined or trapped contained in the metallic nanoparticles however is concentrated near their floor. This phenomenon is scientifically referred to as ‘localized floor plasmon resonances (LSPRs)’. This function provides a terrific superiority to metallic nanoparticles in comparison with their dielectric counterparts, as a result of one may exploit such floor resonances to detect bio-organisms or molecules in drugs or chemistry. Additionally, such floor resonances might be used because the suggestions mechanism essential for laser achieve. In such a means, one can notice a nanoscale tiny laser that may be adopted in lots of future nanophotonic purposes, like mild detection and ranging (LiDAR) for the far-field object detection.”

Based on the researchers, the effectivity of those purposes relies on the resonant Q-factors.

“Sadly, because of the excessive ‘absorptive’ and ‘radiative’ loss in metallic nanoparticles, the LSPRs Q-factors are very low,” mentioned co-lead creator Dr. Orad Reshef, a postdoctoral fellow within the Division of Physics on the College of Ottawa.

“Greater than a decade in the past, researchers discovered a solution to mitigate the dissipative loss by fastidiously arranging the nanoparticles in a lattice. From such ‘floor lattice’ manipulation, a brand new ‘floor lattice resonance (SLR)’ emerges with suppressed losses. Till our work, the utmost Q-factors reported in SLRs was round a couple of hundred. Though such early reported SLRs have been higher than the low-Q LSPRs, they have been nonetheless not very spectacular for environment friendly purposes. It led to the parable that metals usually are not helpful for sensible purposes.”

A delusion that the group was capable of deconstruct throughout its work on the College of Ottawa’s Superior Analysis Advanced between 2017 and 2020.

“At first, we carried out numerical modeling of a gold nanoparticle metasurface and have been shocked to acquire high quality components of a number of thousand,” mentioned Md Saad Bin-Alam, who primarily designed the metasurface construction.

“This worth has by no means been reported experimentally, and we determined to investigate why and to try an experimental demonstration of such a excessive Q. We noticed a really high-Q SLR of worth almost 2400, that’s a minimum of 10 occasions bigger than the biggest SLRs Q reported earlier.”

A discovery that made them notice that there’s nonetheless so much to find out about metals.

“Our analysis proved that we’re nonetheless removed from figuring out all of the hidden mysteries of metallic (plasmonic) nanostructures,” concluded Dr. Orad Reshef, who fabricated the metasurface pattern. “Our work has debunked a decade-long delusion that such constructions usually are not appropriate for real-life optical purposes because of the excessive losses. We demonstrated that, by correctly engineering the nanostructure and punctiliously conducting an experiment, one can enhance the end result considerably.”

Reference: “Extremely-high-Q resonances in plasmonic metasurfaces” by M. Saad Bin-Alam, Orad Reshef, Yaryna Mamchur, M. Zahirul Alam, Graham Carlow, Jeremy Upham, Brian T. Sullivan, Jean-Michel Ménard, Mikko J. Huttunen, Robert W. Boyd and Ksenia Dolgaleva, 12 February 2021, Nature Communications.
DOI: 10.1038/s41467-021-21196-2

The paper is printed in Nature Communications. Md Saad Bin-Alam and Dr. Orad Reshef primarily carried out the analysis. They have been supported by Yaryna Mamchur and Dr. Mikko Huttunen within the experiment and the numerical modeling, respectively. Professors Ksenia Dolgaleva and Robert W. Boyd collectively supervised the analysis in collaboration with Professor Jean-Michel Ménard and Iridian Spectral Inc. The opposite co-authors, Dr. Zahirul Alam and Dr. Jeremy Upham, took half in getting ready the manuscript. Dr. Alam additionally helped with the experimental setup.

By Rana

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