Researchers
develop a new framework for nanoantenna light absorption:
Harnessing light's energy into
nanoscale volumes require novel engineering approaches to overcome the fundamental barrier is known as the "diffraction limit." However,
University of Illinois researchers have breached this barrier by developing
nanoantennas that pack the energy captured from light sources, such as LEDs,
into particles with nanometer-scale diameters, making it possible to detect
individual biomolecules, catalyze chemical reactions and generate photons with
desirable properties for quantum computing.
The results,
which have a broad array of applications that may include better cancer
diagnostic tools, To create a device capable of overcoming the diffraction
limit, graduate student Qinglan Huang and her adviser, Holonyak Lab Director
Brian T. Cunningham, a Donald Biggar Willett Professor in Engineering, coupled
photonic crystals with a plasmonic nanoantenna, an innovative approach in
the field. The photonic crystals serve as light receivers and focus the energy
into an electromagnetic field that is hundreds of times greater than
that received from the original light source, such as an LED or laser. The
nanoantennas, when "tuned" to the same wavelength, absorb the energy
from the electromagnetic field and concentrate the energy into a smaller volume
that is yet another two orders of magnitude of greater intensity. The energy
feedback between the photonic crystal and the nanoantenna, called
"resonant hybrid coupling" can be observed by its effects on the reflected
and the transmitted light spectrum.
To
achieve this, the team carefully controlled the density of the nanoantennas to
maximize their energy collection efficiency. They also developed a method that
allowed the nanoantennas to be distributed uniformly across the photonic
crystal surface and tuned the photonic crystal's optical resonating
wavelength to match the absorption wavelength of the nanoantennas. In addition
to changing how researchers can work with light, this new coupling method has
the potential to change how and when cancer is diagnosed. One application is to
use a gold nanoparticle, not much larger than biomolecules such as DNA, as the
nanoantenna. In this case, the feedback provides a way to identify a biomarker
unique to a certain type of cancer cell, and the group now linking the resonant
hybrid coupling technique to novel biochemistry methods to detect
cancer-specific RNA and DNA molecules with single-molecule precision. The next
steps of this research involve delving into the potential applications of this
new process.Source Credit: Nano Magazine
