A new discovery could help pave way for a much cheaper and less energy consuming high-speed internet connection through the use of nonlinear-optical effects – a technology that allows for thousands of time faster data processing than electronics.
Researchers at University of Texas at Arlington and The University of Vermont have published a paper in journal Nature Communications wherein they have detailed an experimental demonstration of an optical medium in which multiple beams of light can autocorrect their own shapes without affecting one another. This effectively means that it is possible to enables simultaneous nonlinear-optical processing of multiple light beams by a single device without converting them to electrical form paving way for use of the technology in full multi-Terabit per second potential, resulting in cheaper and more energy efficient high-speed internet communications.
As it stands, telecommunications companies resort to frequent optoelectronic regeneration to eliminate the noise accumulated during light propagation in optical communication links. The main issue here is that the companies are required to convert optical signals to electrical via fast photodetectors, process them with silicon-based circuitry, and then convert the electrical signals back to optical, using lasers followed by electro-optic modulators.
Since each optical fiber can carry over a hundred different signals at various wavelengths, known as wavelength-division multiplexing (WDM), such an optoelectronic regeneration needs to be done separately for each wavelength, making regenerators large, expensive and inefficient consumers of power.
An attractive alternative to this is processing the optical signal directly, without converting it to electrical and back. In particular, the speed of light propagating in a transparent medium can be slightly modified by a change in the light intensity. This is a manifestation of a nonlinear-optical effect known as “self-phase modulation” or SPM. If light contains both signal and noise, the SPM can help clean the signal from noise by scattering the noise energy into frequencies well outside the signal band, from where the noise can be easily removed by a filter. When applied to light containing useful data, this SPM-enabled noise-removal operation is called “all-optical regeneration,” which can result in optical auto-correction of the signals carrying hundred times faster data rates than what can be processed electronically.
In their published article researchers demonstrated a novel group-delay-managed nonlinear-optical medium, where strong SPM effect is achieved without such inter-channel interference. Splitting a conventional nonlinear medium, such as an optical fiber, into several short sections separated by special periodic-group-delay filters yields a medium in which all frequency components of the same WDM channel travel with the same speed, ensuring strong SPM. Different WDM channels travel with different speeds, which dramatically suppresses any inter-channel interaction.
The multi-channel regenerator could even potentially shrink to the size of a matchbox in the future if the nonlinear-optical medium could be implemented on a microchip.