Mutual Quantum Coherence among Laser Pulses Key to Reversing Interactions that Slow Fiber-Optic Communications

Researchers have figured out a way to pump more light farther along an optical fiber, offering engineers a potential solution to the so-called "capacity crunch" that threatens to limit bandwidth on the Web.

These findings, which represent a step toward a faster and vaster Internet, show that silica fibers -- the hair-like wires that form the basis of fiber-optic communication -- can handle a lot more data than researchers had originally estimated. Normally, information traveling through an optical fiber is subject to nonlinear distortions that degrade it over time. Consequently, signals must be regenerated along their routes so that the messages they contain aren't garbled when they reach their recipients. Now, Eduardo Temprana and colleagues have found a way to suppress these nonlinear, dissipative effects of light traveling through an optical fiber, eliminating the need for constant (and expensive) signal regeneration. The researchers used digital back-propagation methods to study various frequencies of laser pulses as they traveled through optical fibers more than a thousand meters long. Their observations reveal that the light-induced, nonlinear interactions that slow fiber-optic communications can be reversed -- and that mutual quantum coherence among laser pulses is the key to such reversal. Taken together, the findings suggest that optical fibers are capable of making more bandwidth available and sending more data down the line than researchers had expected.