| |
|
|
Engineering |
| |
Henry
Samueli School of Engineering and Applied Science |
 |
|
| |
|
|
|
Electrical engineering professor Bahram Jalali
and researcher Daniel Solli
UCLA Engineering
researchers capture optical 'rogue waves'
Findings could help resolve mystery of monster ocean waves
Maritime folklore tells tales of
giant "rogue waves" that can appear and disappear
without warning in the open ocean. Also known as "freak
waves," these ominous monsters have been described by mariners
for ages and have even appeared prominently in many legendary
literary works, from Homer's "Odyssey" to "Robinson
Crusoe."
Once dismissed by scientists as fanciful sailors' stories akin
to sea monsters and uncharted inlands, recent observations have
shown that they are a real phenomenon, capable of destroying
even large modern ships. However, this mysterious phenomenon
has continued to elude researchers, as man-made rouge waves
have not been reported in scientific literature — in water
or in any other medium.
Now, researchers at the UCLA Henry Samueli School of Engineering
and Applied Science have succeeded in creating and capturing
rogue waves. In their experiments, they have discovered optical
rogue waves — freak, brief pulses of intense light analogous
to the infamous oceanic monsters — propagating through
optical fiber. Their findings appear in the Dec. 13 issue of
the journal Nature.
 |
|
"Optical rogue waves bear a close connection
to their oceanic cousins," said lead investigator Daniel
Solli, a UCLA Engineering researcher. "Optical experiments
may help to resolve the mystery of oceanic rogue waves, which
are very difficult to study directly."
It is thought that rogue waves are a nonlinear, perhaps chaotic,
phenomenon, able to develop suddenly from seemingly innocuous
normal waves. And while the study of rogue waves has focused
on oceanic systems and water-based models, light waves traveling
in optical fibers obey very similar mathematics to water waves
traveling in the open ocean, making it easier to study them
in a laboratory environment.
Still, detecting a rogue wave is like finding a needle in a
haystack. The wave is a solitary event that occurs rarely, and,
to make matters worse, the timing of its occurrence is entirely
random. But using a novel detection method they developed, the
UCLA research group was able to not only capture optical rogue
waves but to measure their statistical properties as well.
They found that, similar to freak waves in the ocean, optical
rogue waves obey "L-shaped" statistics - a type of
distribution in which the heights of most waves are tightly
clustered around a small value but where large outliers also
occur. While these occurrences are rare, their probability is
much larger than predicted by conventional (so-called normal
or Gaussian) statistics.
"This discovery is the first observation of man-made rogue
waves reported in scientific literature, but its implications
go beyond just physics," said Bahram Jalali, UCLA professor
of electrical engineering and the research group leader. "For
example, rare but extreme events, popularly known as "black
swans," also occur in financial markets with spectacular
consequences. Our observations may help develop mathematical
models that can identify the conditions that lead to such events."
Co-authors on the Nature paper include UCLA Engineering researchers
Claus Ropers and Prakash Koonath. Ropers is also affiliated
with the Max Born Institute for Nonlinear Optics and Short Pulse
Spectroscopy in Germany.
The research was funded by the Defense Advanced Research Projects
Agency (DARPA), the central research and development organization
for the U.S. Department of Defense.
###
12.12.07
M. Chin
|
|
|
|
|
COPYRIGHT
2004 UCLA |
|
