From Optical Rogue Waves to Ocean Monsters

January 8, 2008

Tales of giant "rogue waves" appearing suddenly in the open ocean are no longer dismissed by scientists as fanciful sailors' tales. Recent observations have confirmed their existence. Now, researchers have found an optical analog that may help them demystify these monster ocean waves.

"Optical rogue waves bear a close connection to their oceanic cousins," said Daniel Solli of the University of California, Los Angeles. "Optical experiments may help to resolve the mystery of oceanic rogue waves, which are very difficult to study directly."

Solli and his colleagues reported their findings in the paper "Optical Rogue Waves," published in the Dec. 13 Nature.

Rogue waves are, apparently, a nonlinear — perhaps chaotic — phenomenon, able to develop abruptly from seemingly innocuous normal waves. While the study of rogue waves has focused on oceanic systems and water-based models, light waves traveling in optical fibers, which obey roughly the same mathematical laws as water waves traveling in the open ocean, are the key to unraveling this mystery of the deep.

Solli and his colleagues discovered that, like 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. The probability of these rare occurrences is much greater than that predicted by conventional, or so-called Gaussian, statistics.

"This discovery is the first observation of man-made rogue waves reported in scientific literature, but its implications go beyond just physics," UCLA's Bahram Jalali said. "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."

Source: Nature News, Dec. 12, 2007; University of California, Los Angeles, Dec. 12, 2007.