New material could speed up underwater communications by orders of magnitude

January 24, 2014, University of California - San Diego
Material developed could speed up underwater communications by orders of magnitude
Electrical engineers at UC San Diego have demonstrated that artificial materials can significantly improve the speed of optical communications. The team showed that an artificial metamaterial can increase the light density and blink speed of a fluorescent light-emitting dye molecule. Credit: Liu Research Group/UC San Diego

( —University of California, San Diego electrical engineering professor Zhaowei Liu and colleagues have taken the first steps in a project to develop fast-blinking LED systems for underwater optical communications.

In the January 6 issue of Nature Nanotechnology, Liu and colleagues show that an artificial metamaterial can increase the light intensity and "blink speed" of a fluorescent light-emitting dye molecule.

The nanopatterned layers of silver and silicon in the new material sped up the molecule's blink rate to 76 times faster than normal, while producing an 80-fold increase in its brightness.

"The major purpose of this program is to develop a better light source for communication purposes," Liu said. "But this is just a first step in the whole story. We have proved that this artificial, manmade material can be designed to enhance light emission and intensity, but the next step will be to apply this on conventional LEDs."

Extreme blinking speed – ultrafast modulation – in blue and green LEDs is a missing link that is necessary for increasing the rate at which information can be sent via optical channels through the open water, such as between ships and submarines, submarines and divers, underwater environmental sensors and unmanned underwater vehicles, or other combinations.

If dramatically improved, optical wireless communications could eventually replace underwater acoustic communications systems for short distance applications. Acoustic communications are limited by slow speed and low data rates and may possibly cause distress to whales, dolphins and other marine life. To do this, they must develop blue and green LED systems that blink one or two orders of magnitude faster than today's blue and green gallium nitride (GaN) based LEDs.

Material developed could speed up underwater communications by orders of magnitude
UC San Diego graduate student Dylan Lu is working with electrical engineering professor Zhaowei Liu on a project to develop fast-blinking LED systems for underwater optical communication. Credit: Josh Knoff/UC San Diego Jacobs School of Engineering

In underwater optical wireless communications systems, data is converted from an electrical signal to optical waves that travel through the water from a light source such as a LED to an optical receiver. Blinking blue and green LEDs are already used to transfer information through the water. (Blue and green LEDs are used because their light is less apt to be absorbed by the water than other colors.)

The metamaterials developed by the researchers are synthetic, with properties not found in nature, and are specially designed to accelerate the light generation process.

So far, it's been difficult to directly convert an electrical signal into an optical signal in LEDs with adequate speed. At the moment, the blink rate for most of these converted signals is less than one gigahertz, a rate slower than the speed of most WiFi signals, Liu said.

The materials are designed to have extremely strong interactions with the light emitters that are specific to the wavelength—or color—of the emissions. In the new report, the researchers used a dye molecule that gives off a yellow-green hue. So the next step will be to pair the materials with the blue and green LEDs.

"The design of the materials may not be the hardest thing," said UC San Diego graduate student Dylan Lu, the lead author of the Nature Nanotechnology paper, who noted that they will work with LEDs that have been manufactured to a specific industry standard. "I think the major challenge, to apply it to LEDs, will be an integration issue."

Liu recently won a grant from the Office of Naval Research (ONR) to develop the fast-blinking blue and green LED systems, which includes a little more than $500,000 over three years.

Along with Electrical and Computer Engineering professors Paul Yu and Eric Fullerton, Liu aims to eventually test ultrafast blinking LED configurations in San Diego's ocean waters.

"We started from advances in fundamental material research, and we want to transfer the knowledge to the LED business," said Liu.

Explore further: Researchers test effects of LEDs on leaf lettuce

Related Stories

Researchers test effects of LEDs on leaf lettuce

November 19, 2013

In the life cycle of plants, most developmental processes are dependent on light. Significant biological processes such as germination, shade avoidance, circadian rhythms, and flower induction are all affected by light. Recent ...

New material gives visible light an infinite wavelength

October 13, 2013

Researchers from the FOM Institute AMOLF and the University of Pennsylvania have fabricated a material which gives visible light a nearly infinite wavelength. The new metamaterial is made by stacking silver and silicon nitride ...

Bright, laser-based lighting devices

September 27, 2013

As a modern culture, we crave artificial white lights—the brighter the better, and ideally using less energy than ever before. To meet the ever-escalating demand for more lighting in more places and to improve the bulbs ...

Zeroing in on the elusive green LED

April 25, 2011

Researchers at Rensselaer Polytechnic Institute have developed a new method for manufacturing green-colored LEDs with greatly enhanced light output.

Laser diodes versus LEDs

November 11, 2013

Solid-state lighting based on light-emitting diodes (LEDs) is the most efficient source of high color quality white light. Nevertheless, they show significant performance limitations such as the "efficiency droop". Blue laser ...

Recommended for you

Quantum dot ring lasers emit colored light

January 22, 2018

Researchers have designed a new type of laser called a quantum dot ring laser that emits red, orange, and green light. The different colors are emitted from different parts of the quantum dot—red from the core, green from ...

Fast computer control for molecular machines

January 19, 2018

Scientists at the Technical University of Munich (TUM) have developed a novel electric propulsion technology for nanorobots. It allows molecular machines to move a hundred thousand times faster than with the biochemical processes ...


Adjust slider to filter visible comments by rank

Display comments: newest first

2 / 5 (1) Jan 24, 2014
"short distance applications"

How short?
not rated yet Jan 24, 2014
depends on how bright the light is and how much the water absorbs. Presumably as long as you (or sufficiently well equipped photodetectors) could see the light, you have data transmission
not rated yet Jan 25, 2014
One GHz, using even the most simple modulation, sounds like a reasonably sized space through which information might be pushed. How much more is needed?. The 802.11 reference is misleading, A better comparison would be the wired LAN connection you might have at work. Few wireless connections over the air (802.11, 4G, Bluetooth, etc.) approach that speed (i.e. 1Gbit/s).

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.