Using all-optical controls could speed the transmission of telecommunications data, but optical switches that can work at high bandwidths need a lot of energy to turn on and off. So the usual approach is that telecom providers deploy systems that convert light into electrical signals to process the data, then back into light for transmission.

Light work: Michelle Povinelli uses mathematical modeling to study how light moves through structures. Credit: Technology Review

Now theoretical work from researchers at the University of Southern California and Stanford University suggests a way to get around this trade-off between bandwidth and power. Their simulations suggest that controlling the input beam by using new ways of shaping light pulses should allow switching at lower power. If these effects can be demonstrated in the lab, they could lead to new devices for speedier, energy-efficient telecommunications.

Optical signal processing has high power requirements because it takes a lot of energy to get photons to interact with one another. One way to encourage these interactions is to increase the intensity of the light beams. The more intense the pulse, the more power it takes to produce, but the more likely it is to interact with another pulse.