Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Squeezing light at the nanoscale

18.06.2018

Ultra-confined light could detect harmful molecules

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new technique to squeeze infrared light into ultra-confined spaces, generating an intense, nanoscale antenna that could be used to detect single biomolecules.


Nano-discs act as micro-resonators, trapping infrared photons and generating polaritons. When illuminated with infrared light, the discs concentrate light in a volume thousands of times smaller than is possible with standard optical materials. At such high concentrations, the polaritons oscillate like water sloshing in a glass, changing their oscillation depending on the frequency of the incident light.

Credit: Harvard SEAS

The researchers harnessed the power of polaritons, particles that blur the distinction between light and matter. This ultra-confined light can be used to detect very small amounts of matter close to the polaritons. For example, many hazardous substances, such as formaldehyde, have an infrared signature that can be magnified by these antennas. The shape and size of the polaritons can also be tuned, paving the way to smart infrared detectors and biosensors.

The research is published in Science Advances.

"This work opens up a new frontier in nanophotonics," said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, and senior author of the study. "By coupling light to atomic vibrations, we have concentrated light into nanodevices much smaller than its wavelength, giving us a new tool to detect and manipulate molecules."

Polaritons are hybrid quantum mechanical particles, made up of a photon strongly coupled to vibrating atoms in a two-dimensional crystal.

"Our goal was to harness this strong interaction between light and matter and engineer polaritons to focus light in very small spaces," said Michele Tamagnone, postdoctoral fellow in Applied Physics at SEAS and co-first author of the paper.

The researchers built nano-discs -- the smallest about 50 nanometers high and 200 nanometers wide -- made of two-dimensional boron nitride crystals. These materials act as micro-resonators, trapping infrared photons and generating polaritons. When illuminated with infrared light, the discs were able to concentrate light in a volume thousands of times smaller than is possible with standard optical materials, such as glass.

At such high concentrations, the researchers noticed something curious about the behavior of the polaritons: they oscillated like water sloshing in a glass, changing their oscillation depending on the frequency of the incident light.

"If you tip a cup back-and-forth, the water in the glass oscillates in one direction. If you swirl your cup, the water inside the glass oscillates in another direction. The polaritons oscillate in a similar way, as if the nano-discs are to light what a cup is to water," said Tamagnone.

Unlike traditional optical materials, these boron nitride crystals are not limited in size by the wavelength of light, meaning there is no limit to how small the cup can be. These materials also have tiny optical losses, meaning that light confined to the disc can oscillate for a long time before it settles, making the light inside even more intense.

The researchers further concentrated light by placing two discs with matching oscillations next to each other, trapping light in the 50-nanometer gap between them and creating an infrared antenna. As light concentrates in smaller and smaller volumes, its intensity increases, creating optical fields so strong they can exert measurable force on nearby particles.

"These light-induced forces serve also as one our detection mechanisms," said Antonio Ambrosio, a principal scientist at Harvard's Center for Nanoscale Systems. "We observed this ultra-confined light by the motion it induces on an atomically sharp tip connected to a cantilever."

A future challenge for the Harvard team is to optimize these light nano-concentrators to achieve intensities high enough to enhance the interaction with a single molecule to detectable values.

###

This research was co-authored by Kundan Chaudhary, Luis A. Jauregui, Philip Kim and William L. Wilson. It was supported by the National Science Foundation and the Swiss National Science Foundation.

Media Contact

Leah Burrows
lburrows@seas.harvard.edu
617-496-1351

 @hseas

http://www.seas.harvard.edu/ 

Leah Burrows | EurekAlert!

Further reports about: Harvard boron nitride discs infrared light nanometers nanoscale optical materials oscillate

More articles from Physics and Astronomy:

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>