US scientists are promising ultra fast optical communications after demonstrating a “milestone” technique that allows them to control the spectral properties of ultrafast light pulses.

The Engineers at Purdue University have been experimenting with laser pulse strobes with flashes lasting a trillionth or quadrillionth of a second - a picosecond or femtosecond, respectively.

Precisely controlling the intensity of these pulses, which is called "pulse shaping," will enable them to tune the laser pulses to suit specific applications, said Andrew Weiner, Distinguished Professor of Electrical and Computer Engineering at Purdue.

Researchers at other institutions have developed ultrafast lasers producing trains of pulses that are split into hundreds of thousands of segments, with each segment representing a different portion of the spectrum making up a pulse.

The segments are called "comb lines" because they resemble teeth on a comb when represented on a graph, and the entire pulse train is called a " femtosecond frequency comb."

In the new research, the Purdue engineers precisely "shaped" 100 comb lines from such a frequency comb in a single pulse.

"There are still huge technological challenges ahead, but we really see 100 comb lines as a milestone, a significant step," Weiner said. The research is based at Purdue's Ultrafast Optics and Optical Fiber Communications Laboratory.

The research is funded by the National Science Foundation and the Defense Advanced Research Projects Agency, or DARPA.