Applied Physics

Putting a Twist on Multiplexing

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Science  31 Jan 2014:
Vol. 343, Issue 6170, pp. 463
DOI: 10.1126/science.343.6170.463-b

Light is a versatile medium for communication, with the optic fibers that span the globe forming the backbone of our Internet and communications industry. The insatiable hunger for even higher data rates and a faster Internet requires more light to be pumped along the fiber network. There is, however, a limit to how much light you can put into a fiber before optical nonlinearities are induced and the communications channel is corrupted. The traditional solution is to multiplex the various modes of light (wavelength and polarization, for instance) so the information is encoded in a number of channels (split between multiple wavelengths and polarization states) sent down the fiber in parallel, and then de-multiplexed at the other end: The aggregated data rate is boosted by the number of channels used. Recent work has explored the optical angular momentum of light, wherein the light is structured or twisted like a spiral and carries quantized units of angular momentum as it propagates. In a free-space demonstration, Huang et al. show that multiplexing wavelength, polarization, and optical angular momentum enables data transmission rates in excess of 100 Tbit/s. Transferring such a route of multiple multiplexing to optic fibers should stave off our hunger for faster data rates for a little while yet.

Opt. Lett. 39, 197 (2014).

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