News

Solitons in silicon photonic crystal chips



16 January 2014


Ms Andrea Blanco-Redondo and Dr Chad Husko from CUDOS (ARC Centre of Excellence for Ultrahigh bandwidth Devices for Optical Systems) at the University of Sydney's School of Physics have led an international research team to observe on-chip soliton compression in a silicon photonic crystal for the first time. The research builds on a long-standing collaboration in silicon photonics between the University of Sydney, the University of St Andrews and the University of York, as well as new partner Sun Yat-sen University in Guangzhou, China. The results will appear in Nature Communications on January 15th, 2014.

Ms Andrea Blanco-Redondo, Dr Chad Husko, and Professor Ben Eggleton at their Soliton compression experiment.
Ms Andrea Blanco-Redondo, Dr Chad Husko, and Professor Ben Eggleton at their Soliton compression experiment.

"Optical soliton waves in a silicon photonic crystal chip the size of a human hair could add key insight to future integrated optical communications systems," said Dr Husko

In their simplest embodiment, solitons are nonlinear waves that propagate through a medium undistorted. One of the most striking natural examples are rogue waves, enormous water waves capable of toppling ocean going vessels.

"Due to their ubiquitous appearance in diverse physical systems including, plasmas, proteins, magnetism, and optics, solitons are arguably the most fundamental nonlinear wave," said Dr Husko

This is just the beginning, from here there are many other fascinating phenomena left to explore from this experiment - Ms Blanco-Redondo.


In the ideal case, the soliton behaviour in silicon would be similar to that in a glass media, such as optical fibres. In practice, however, the composition of the silicon waveguide drastically changes the picture, and hindered the observation in silicon photonic crystals until now.

"The observations of soliton compression presented in this paper unveil a significantly different soliton regime and interestingly, the pulse undergoes acceleration therefore arrives before the standard soliton, said Ms Blanco-Redondo

In addition to basic research, applications of solitons include ultrabright 'supercontinuum' white light sources that enabled the metrology experiment honoured with the 2005 Nobel Prize.

Further, the understanding of solitons in optical fibres played a key role in the development of long-haul optical telecommunications and continues to inform how we send terabits of data down them today.

"I am delighted with this latest breakthrough which is of both fundamental and technological importance and builds on almost 20 years of my own research in optical solitons and photonic crystals," said Professor Eggleton, CUDOS Director and Co-author.

Scanning electron micrograph image of the slow-light silicon photonic crystal waveguide.
Scanning electron micrograph image of the slow-light silicon photonic crystal waveguide.

"Our experiments will inform the ongoing push to develop optical circuits in CMOS-compatible materials such as silicon for on-chip communication, similar to the community's research in glass fibre in the 1980's," said Dr. Husko.

The team is pursuing this avenue of research in line with the mission of CUDOS to develop photonic chips that are 'faster, smaller, greener.'

In contrast to kilometre fibres, the soliton propagation occurs at the micron scale, the size scale of human hair, due to slow-light in the photonic crystal device. These results could allow for the miniaturisation of optical components featuring soliton-based functionality in integrated silicon photonic chips.

Click here to read the journal paper


Contact: Tom Gordon

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