'Tsunami' on a silicon chip: a world first for light waves

University of Sydney

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.

A collaboration between the University of Sydney Nano Institute and Singapore University of Technology and Design has for the first time manipulated a light wave, or photonic information, on a silicon chip that retains its overall ‘shape’.

Such waves – whether a tsunami or a photonic packet of information – are known as ‘solitons’. The Sydney-Singapore team has for the first time observed ‘soliton’ dynamics on an ultra-silicon-rich nitride (USRN) device fabricated in Singapore using state-of-the-art optical characterisation tools at Sydney Nano.

This foundational work, published today in Laser & Photonics Reviews, is important because most communications infrastructure still relies 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.

Ezgi Sahin, a PhD student at SUTD conducted the experiments with Dr Andrea Blanco Redondo at the University of Sydney.

“The observation of complex soliton dynamics paves the way to a wide range of applications, beyond pulse compression, for on-chip optical signal processing,” Ms Sahin said. “I’m happy to be a part of this great partnership between the two institutions with deep collaboration across theory, device fabrication and measurement.”

Co-author of the study and Director of Sydney Nano, Professor Ben Eggleton, said: “This represents a major breakthrough for the field of soliton physics and is of fundamental technological importance.

“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.”

Professor Dawn Tan, a co-author of the paper at SUTD, said: “We 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) we used. This platform prevents loss of information which has compromised previous demonstrations.”

Bragg Soliton Compression and Fission on CMOS‐Compatible Ultra‐Silicon‐Rich Nitride

Ezgi Sahin, Andrea Blanco‐Redondo, Peng Xing, Doris K. T. Ng, Ching E. Png, Dawn T. H. Tan, Benjamin J. Eggleton

Laser & Photonics Reviews 2019

DOI: https://doi.org/10.1002/lpor.201900114

Contact information:

Professor Ben Eggleton

Director of University of Sydney Nano Institute

benjamin.eggleton@sydney.edu.au

Tel: +61 2 9351 3604

Fax: +61 2 9351 7726

Lab: Photonics and Optical Physics group

Professor Dawn Tan

Singapore University of Technology and Design (SUTD)

dawn_tan@sutd.edu.sg

Tel: +65 6499 4607

Lab: Photonics Devices and Systems group