Soliton makes its way across silicon in CUDOS experiment

'Intricate' research paves way to glass-free on-chip interconnect

The CUDOS silicon waveguide

On-chip photonic interconnects are a step closer, with a successful demonstration of soliton compression in silicon from Australia's CUDOS research centre.

In a Nature Communications report, a team from CUDOS demonstrates that solitons can be both observed and harnessed in silicon-based photonic systems. Solitons in fibre optic systems, for example, have good stability over long distances.

CUDOS director Professor Ben Eggleton told The Register that although solitons are “well established and well exploited” in many fields, solitons on silicon pose particular problems. “Silicon causes non-linearity, which allows the soliton to not disperse,” he explained.

However, light interacts with silicon causing the release of electrons – and those electrons absorb light. So a challenge in making practical use of solitons in silicon-based photonics is to have them propagate across silicon without changing shape.

The second fundamental aspect of the research, Professor Eggleton said, is that the research team, led by Andrea Blanco-Redondo and Dr Chad Husko, were able to shape the light pulses in silicon.

The CUDOS silicon waveguide

The silicon waveguide CUDOS developed

to demonstrate soliton compression

“Compressing the pulse is the foundation of all photonic communication,” he said, because that enables systems in which different pulse shapes can represent ones and zeroes.

“This experiment is laying down the foundation, by elucidating the non-linear dynamics” of soliton behaviour in silicon systems, he said, describing the work as “exquisite and intricate”.

While the CUDOS experiment only worked at a few hundred bits per second, Eggleton said, the picosecond pulse width the researchers worked with means that communication rates of 100 Gbps are feasible.

On-chip photonic interconnect is keenly researched, because using light for the interconnect reduces the amount of heat a chip has to dissipate.

The CUDOS work has been published in Nature Communications. The full paper is here. ®

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