Nano-Antennas Transmit, Receive Light as Radio Waves
R. Colin Johnson | Date: 10-23-09 | Comments: 1
- Nano-antennas are so small that they operate at the same frequencies as light waves, enabling information to be transmitted by optical-frequency radios that can transmit data up to a million times faster that radios today.
The fact that radio waves behave like light--exhibiting optical
properties like reflection, refraction, diffraction and
interference--was demonstrated back in 1887 in Karlsruhe, Germany, by
Heinrich Hertz (after whom Hz was named). Since then radios have gone
to higher and higher frequencies, enabling more and more data to be
communicated, but making the antennas for transmission and reception
smaller and smaller. Now researchers at the Karlsruhe Institute of
Technology (KIT) have come full circle, demonstrating nano-antennas so
small that they operate at the same frequencies as light waves,
enabling information to be transmitted by optical-frequency radios that
can transmit data up to a million times faster that radios today.
KIT scientists claim to have created the world's smallest antennas
using the same principles as traditional radio antennas, which transmit
and receive radio waves best when they measure about half the
wavelength of the signal. Light waves operate at ultra-high frequencies
compared to the GHz frequencies typical of electronic devices today,
making their antennas corresponding small. For instance, yellow light
is about 500,000 GHz, corresponding to a wavelength of about 600
nanometers. To transmit and receive radio waves at those frequencies
would require an antenna around 300 nanometers. Other researchers have
reported progress toward creating optical frequency antennas that
small, but KIT scientists claim that they have the world's first
technique that could be used to mass produce nanoantennas.
The gold nanoantennas were fabricated by Hans-Jurgen Eisler and
Matthias Wissert at the Light Technology Institute at KIT. The team
used electron-beam lithography to sculpt the tiny devices. In tests,
these nanoantenna were able to send and receive optical data at speeds
thousands of times faster than today's fastest radios. For instance,
using antennas in the range of 400-to-1000 nanometers, data could be
wirelessly transmitted and received at speeds about 10,000 times faster
than today. For the future, the KIT scientists believe they can
fabricate antennas significantly smaller than 100 nanometers,
potentially enabling future optical-frequency radios to operate at
speeds up to a million times faster than the fastest radio
communications today.
Besides communications, these nanoantennas could also be used to
optically image tiny structures that have been too small to observe
until now. For instance, nanoantennas could focus light in spots as
small as 10 nanometers--about the size of individual biomolecules,
which have been too small to image before now. Nanoantennas could also
be used to produce images of many tiny man-made structures, such as
electronic sensors, transistors and other small semiconductor
structures. As a transmitter, the tiny nanoantennas could also be used
to emit streams of individual photons for a variety of laboratory
applications, including the optimization of photovoltaic modules.
Next the KIT researchers plan to further refine their electron-beam
lithography techniques in order to fabricate even smaller antenna, as
well as optimize their current designs and demonstrate working radios
using their nanoantennas.
