A collaboration between the University of Sydney’s Sydney Nano Institute and Singapore University of Technology and Design (SUTD) has the potential to improve photonic communications devices and infrastructure.
According to a recent press release, the Sydney-Singapore team has manipulated a light wave, or photonic information, on a silicon chip that retains its overall shape.
Similarly, a tsunami holds its wave shape over very long distances across the ocean, retaining its power and information far from its source.
In communications science, retaining information in an optic fibre that spans continents is vital.
Ideally, this requires the manipulation of light in silicon chips at the source and reception end of the fibre without altering the wave shape of the photonic packet of information.
Doing so has eluded scientists until now.
‘Solitons’ are the aforementioned waves, whether a tsunami or a photonic packet of information.
The team was able to observe ‘soliton’ dynamics on an ultra-silicon-rich nitride (USRN) device fabricated in Singapore using state-of-the-art optical characterisation tools at Sydney Nano.
Benefits of the study
The work is essential because most of the communications infrastructures still rely on silicon-based devices for propagation and reception of information.
Manipulating solitons on-chip could potentially allow for the speed up of photonic communications devices and infrastructure.
According to the PhD student from SUTD, the observation of complex soliton dynamics paves the way to a wide range of applications, beyond pulse compression, for on-chip optical signal processing.
The Co-Author of the study and Director of Sydney Nano explained that this represents a major breakthrough for the field of soliton physics and is of fundamental technological importance.
Studying Solitons
He expounded, “Solitons of this nature – so-called Bragg solitons – were first observed about 20 years ago in optical fibres but have not been reported on a chip because the standard silicon material upon which chips are based constrains the propagation. This demonstration, which is based on a slightly modified version of silicon that avoids these constraints, opens the field for an entirely new paradigm for manipulating light on a chip.”
The Co-Author of the paper at SUTD added that they were able to convincingly demonstrate Bragg soliton formation and fission because of the unique Bragg grating design and the ultra-silicon-rich nitride material platform (USRN) used.
This platform prevents loss of information which has compromised previous demonstrations.
Optical soliton waves have been studied since the 1980s in optical fibres and offer enormous promise for optical communication systems because they allow data to be sent over long distances without distortion.
Bragg solitons, which derive their properties from Bragg gratings, can be studied at the scale of chip technology where they can be harnessed for advanced signal processing.
Bragg gratings are periodic structures etched in to the silicon substrate. The silicon-based nature of the Bragg grating device also ensures compatibility with complementary metal oxide semiconductor (CMOS) processing.
The ability to reliably initiate soliton compression and fission allows ultrafast phenomena to be generated with longer pulses than previously required.
The chip-scale miniaturisation also advances the speed of optical signal processes in applications necessitating compactness.
