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Bell Labs scientists find novel optical fibers in deep-sea
sponges
Taken from Lucent site
August
21, 2003 - Scientists from Lucent Technologies' Bell Labs have
found that a deep-sea sponge contains optical fiber that is remarkably similar to
the optical fiber found in today's state-of-the-art telecommunications
networks. The deep-sea sponge's glass fiber, which developed through the course
of evolution, may possess certain technological advantages over industrial
optical fiber, the scientists report in the Aug. 21 issue of the journal Nature.
"We
believe this novel biological optical fiber may shed light upon new
bio-inspired processes that may lead to better fiber optic materials and
networks," said Joanna Aizenberg, the Bell Labs materials scientist who
led the research team. "Mother Nature's ability to perfect materials is
amazing, and the more we study biological organisms, the more we realize how
much we can learn from them."
The
discovery of marine optical fiber is the latest Bell Labs contribution in the
emerging field of science known as biomimetics, which takes engineering
principles from the natural world and applies them to man-made materials and
technologies.
A Structure Similar to Industrial Optical Fiber
The
sponge in the study, Euplectella, lives in the depths of the ocean in
the tropics and grows to about half a foot in length. Commonly known as the
Venus Flower Basket, it has an intricate cylindrical mesh-like skeleton of glassy
silica and a pair of mating shrimp often lives inside it. At the base of the
sponge's skeleton is a tuft of fibers that extends outward like an inverted
crown. Typically, these fibers are between two and seven inches long and about
the thickness of a human hair.
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A close-up look
at the intricate cylindrical mesh-like skeleton of glassy silica of the Venus
Flower Basket. Click the image above to enlarge. |
The
Bell Labs team found that each of the sponge's fibers is composed of distinct
layers with different optical properties. Concentric silica cylinders with high
organic content surround an inner core of high-purity silica glass, a structure
similar to industrial optical fiber, in which layers of glass cladding surround
a glass core of slightly different composition. The researchers found during
experiments that the biological fibers of the sponge conducted light when
illuminated, and used the same optical principles that modern engineers have
used to design industrial optical fiber. "These biological fibers bear a striking
resemblance to commercial telecommunications fibers, as they use the same
material and have similar dimensions," said Aizenberg.
...and Stronger
Though
these natural bio-optical fibers do not have the superbly high transparency
needed for modern telecommunication networks, the Bell Labs researchers found
that these fibers do have a big advantage in that they are extremely resilient
to cracks and breakage. Although extremely reliable, one of the main causes for
outages in commercial optical fiber is fracture resulting from crack growth
within the fiber. Infrequent as an outage is, when it occurs, replacing the
fiber is often a costly, labor-intensive proposition, and scientists have
sought to make fiber that is less susceptible to this problem.
The
sponge's solution is to use an organic sheath to cover the biological fiber,
Aizenberg and her colleagues discovered. "These bio-optical fibers are
extremely tough," she said. "You could tie them in tight knots and,
unlike commercial fiber, they would still not crack. Maybe we can learn how to
improve on existing commercial fiber from studying these fibers of the Venus
Flower Basket," she said.
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Bell Labs
scientist Joanna Aizenberg holding a deep sea sponge that grows its own
highly advanced optical fibers. Click the image above to enlarge. |
Learning from Nature
Another
advantage of these biological fibers is that they are formed by chemical
deposition at the temperature of seawater. Commercial optical fiber is produced
with the help of a high-temperature furnace and expensive equipment. Aizenberg
said, "If we can learn from nature, there may be an alternative way to
manufacture fiber in the future."
Should
scientists succeed in emulating these natural processes, they may also help
reduce the cost of producing optical fiber. "This is a good example where
Mother Nature can help teach us about engineering materials," said Cherry
Murray, senior vice president of physical sciences research at Bell Labs.
"In this case, a relatively simple organism has a solution to a very
complex problem in integrated optics and materials design. By studying the
Venus Flower Basket, we are learning about low-cost ways of forming complex
optical materials at low temperatures. While many years away from being applied
to commercial use, this understanding could be very important in reducing the
cost and improving the reliability of future optical and telecommunications
equipment."
Other
members of the research team were Bell Labs materials scientists Vikram Sundar
and John Grazul, as well as zoologist Micha Ilan of Tel Aviv University and
optics researcher Andrew Yablon of OFS Laboratories.
Bell Labs and Biomimetics
The
study of biomimetics at Bell Labs is part of the quest to find better materials
for technology and industry, and has proved remarkably fruitful. Two years ago,
Aizenberg and her collaborators made the surprising discovery that thousands of
chalk-like calcite crystals spread throughout the exoskeletons of brittlestars,
starfish-like marine invertebrates, collectively form an unusual kind of
compound eye for the animals. The brittlestar's calcite microlenses expertly
compensate for birefringence and spherical aberration, two common types of
distortions in lenses. This led the Bell Labs scientists to attempt to mimic
nature's success and design crystals based on the brittlestar model, with the
ultimate goal of building complex arrays of microlenses similar to the
brittlestar's own lenses.
Earlier
this year, Aizenberg and her colleagues developed a new crystallization
approach that allowed them to directly fabricate single crystals of calcite
that were about one-tenth of a centimeter across. These had patterns less than
ten micrometers across, which is approximately one-tenth the diameter of a human
hair — an approach that may revolutionize how crystals are made in the future
for a wide variety of applications.
Single
crystals patterned at the micron scale or smaller and integrated into
opto-electronic circuits are important components needed to engineer highly
advanced electronic, sensory and optical devices.
Discoveries in recent years include an enzyme that
improves laundry detergent, taken from bacteria that break down fats in cold
water; a glowing protein from jellyfish that allows surgeons to illuminate
cancerous tissue while they operate to remove it; and another enzyme that
improves DNA testing, drawn from bacteria that live near hydrothermal vents at
the ocean bottom.
Kochevar said the sponge study follows an earlier
discovery by Aizenberg
that a starfish called the
brittlestar is coated with tiny lenses that act as a collective “eye,” offering
engineers a model for creating sensors and guidance systems. Both
discoveries show how valuable life in the ocean can be to society and how much
of the ocean remains to be explored, he said.
“It’s incredible, really. We’re looking at these
things that are not known to be visual animals yet we’re finding these
fascinating optical properties that are built into their bodies,” Kochevar
said.
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Posted August 30, 2003