CUDOS

Scratches in glass break electronic traffic jam

Australian breakthrough could deliver 1000 times the bandwidth

Sydney: Presentation at 11.45 Tuesday, 25 October 2005, Hilton Sydney, level 4, room 3.

A small ‘smart’ scratch in a piece of glass is set to replace the electronic components in global fibre optics networks, letting us reach data speeds up to one thousand times greater than currently possible.

Researchers at CUDOS, the Sydney-based Centre for Ultrahigh Bandwidth Devices for Optical Systems, announced their breakthrough today at an international optics conference - LEOS - in Sydney. They also announced a suite of other developments towards their ultimate goal – light-powered switching transistors and light-powered computers.

Light in fibre-optic cables carries data at speeds and quantities far greater than the old copper phone lines – that’s why fibre-optics are the backbone of Australian communications and of the global internet. But every so often the light signals need to be cleaned up, amplified and retransmitted. Currently, we do that with electronic circuits which are much slower than light. These amplifiers are becoming a bottleneck on the internet.

“Our discovery will clear this bottleneck” says Ben Eggleton, Director of CUDOS.

“To get more bandwidth, we need new technology that’s faster than electrons – and light’s the fastest. We just need to build the components that can handle it. And now we’ve got one of the first problems solved,” he says.

CUDOS have developed a small plate of glass with a carefully engineered scratch in it that can regenerate a new clean signal from an old noisy one. The glass is just placed in the light flow. The “smart” scratch first separates out the signal from the noise as the light is guided along it. The light then passes through a series of finely etched channels that recognise which bits are the separated signal and which bits are noise, and allow only the signal pulses past. Any noise is trapped by the channels.

CUDOS have tested this device at speeds over ten times higher than the fastest cables in use in Australia.

“We hope to see the technology implemented over the next decade by the major data carriers as new ultrahigh bandwidth communications systems are rolled out,” says Ben.

With this looming traffic jam cleared, the next challenge for CUDOS is to build an optical switch - the light equivalent of the transistor switch. The invention of the transistor in 1947 triggered the electronic age – an Intel Pentium 4 computer chip can have up to one hundred million transistors.

During the LEOS conference, CUDOS team members from the University of Sydney; Australia National University; Macquarie University; Swinburne University and the University of Technology, Sydney, will also be announcing some of the steps they’ve made towards a light switching ‘transistor’ and a photonic chip – the building block of ultra-fast light powered computers. LEOS is Lasers and Electro-Optics Society of the IEEE ((the worldwide Institute for Electrical and Electronic Engineers)

Background information on CUDOS and conference abstracts are available online at www.scienceinpublic.com.

For further information and interviews contact Ben Eggleton on 0413 385 715, Jacob O'Shaughnessy, Media Officer, University of Sydney, Tel: +61 (2) 9351 4312, mobile: 0421 617 861, jacob@media.usyd.edu.au or Niall Byrne on 0417 131 977, niall@scienceinpublic.com

CUDOS is a research consortium between five Australian Universities: The University of Sydney, Macquarie University, University of Technology Sydney, Australian National University and Swinburne University of Technology.

Funding comes from the Australian Research Council under the Centres of Excellence program, the five universities and from the NSW State Government.

The Research Director is Professor Ben Eggleton, with Professor Yuri Kivshar as Deputy Director. In 2004 the Prime Minister awarded Ben Eggleton the Malcolm McIntosh Prize for Physical Scientist of the Year (link to media releases and background below).

Most of our telecommunications backbones now run on fibre optics. Fibre optics carrying photons of light give us much greater speed and carrying capacity than electron-based transmission. The signal processing though is still done with electronics components, that clean and regenerate signals, reamplify and retransmit them, buffer data, and monitor the network for problems and faults. The electronics components are made with transistors, which we won’t be able to make much smaller or faster. But our demands for high speed transmission of data are still going up. So these signal processing components are becoming bottlenecks on the network. If we could go all-optical it would solve our current speed limitations.

Current network speeds can reach up to 40 gigabits per second. CUDOS expect to develop components that will work at 160 gigabits per second and beyond. The physics of photonic interactions compared to electronic interactions means that light starts reaching its carrying capacity at a data speed about 10,000 times greater than electrons can manage.

Some optical components have been built and demonstrated previously but they don’t offer the same advantages of size and manufacturability that a silicon integrated circuit chip does.

CUDOS have built an effective signal regenerator that compares in size to a silicon chip, and are continuing to research other components to replace electronic network devices. They plan over five years to develop these concepts and miniaturise them into an integrated photonic chip that can replace the electronic silicon chips being used in our networks.

A signal regenerator needs to have some way of distinguishing the signal from the noise and then separating out the noise so that only the signal is passed on.

The idea of a Mamyshev regenerator (what CUDOS have built) is that it uses a non-linear material to distinguish signal and noise. Non-linear because the stronger (more powerful) that a light pulse passing through is, the more its frequency is changed by the material. So as long as your signal is still louder than the noise, its frequency will be changed more. Put a band-pass filter on the end of this material to allow only your highly-changed frequencies through, and you get a clean signal with none of the noise.

CUDOS found that chalcogenide glass – glass doped with sulphur, selenium and tellurium – worked as a non-linear separator. Signal pulses passing through an optical waveguide in the glass separated to a different, broader frequency range than the noise did. That gave them the first half of the regenerator. To create the band-pass filter, they etched a frequency-selective diffraction grating into the waveguide that would filter out any of the noise. The results showed a clean, accurate signal with the noise removed.

LEOS is the IEEE Lasers and Electro-Optics Society (IEEE is the Institute for Electrical and Electronic Engineers, worldwide)

That paper’s conclusions: CUDOS has demonstrated experimentally the first integrated pulse regenerator using a non-linear waveguide followed by linear filtering through a double Bragg grating band-pass filter. They achieve good agreement between their theory and experimental results. Session details:

Integrated All-Optical Chalcogenide Waveguide Pulse Regenerator: Experiment and Modeling

V. G. Ta'eed, M. Shokooh-Saremi, CUDOS, University of Sydney, Sydney, NSW, Australia, L. Fu, D. Moss, M. Rochette, I. C. M. Littler, University of Sydney, Sydney, NSW, Australia, B. J. Eggleton, CUDOS, University of Sydney, NSW, Australia, Y. Ruan and B. Luther-Davies, Australian National University, Canberra, ACT, Australia

We present an integrated, all-optical, chalcogenide waveguide pulse regenerator based on linear filtering of self phase modulated pulses. We demonstrate a nonlinear transfer function with 1.5 ps optical pulses and find good agreement with theory.

TuF1 08.30 - 09.00 (Invited)
Optically-Induced Lattices as Tunable Nonlinear Photonic Crystals, D. N. Neshev, C. R. Rosberg, R. Fischer, A. A. Sukhorukov, A. S.
Desyatnikov, E. A. Ostrovskaya, T. Alexander, W. Z. Krolikowski and Y. S.
Kivshar, Australian National University, Canberra, ACT, Australia By using optically-induced photonic lattices as tunable periodic structures, we demonstrate the key aspects of light propagation in periodic medium, as selective excitation of eigenmodes, diffraction control, and nonlinear beam focusing, shaping and interactions.

TuF3 09.30 - 09.45
Spatial Switching in Modulated Photonic Lattices I. L. Garanovich, A. A. Sukhorukov and Y. S. Kivshar, Australian National University, Canberra, ACT, Australia We discuss propagation and switching of discrete solitons in modulated optically induced photonic lattices. We reveal novel dynamical regimes for strongly localized solitons and show the possibility of binary spatial switching realized by varying the amplitude of the modulating beam.

TuN5 11.45 - 12.15 (Invited)
High Nonlinearity Chalcogenide, Waveguide based All-Optical, Regeneration Schemes, B. J. Eggleton, D. Moss, M. Rochette, V. G. Ta’eed, L. Fu, and I. C. M. Littler, CUDOS, University of Sydney, NSW, Australia We review our recent progress in demonstrating low-power, compact all-optical regeneration schemes suitable for ultrahigh bit-rates (>100Gb/s) based on highly nonlinear chalcogenide optical waveguides.
Self-phase modulation schemesare demonstrated in chalcogenide singlemode fibre and integrated chalcogenide rib waveguides incorporating photosensitively written Bragg gratings.

TuR2 14.00 - 14.15
Evanescent Coupling to Chalcogenide, Glass Photonic Crystal Waveguides via Tapered Microstructured Optical Fibre Nanowires, C. Grillet, D. Moss, E. Magi, University of Sydney, Sydney, NSW, Australia, D. Freeman, S. Madden, B. Luther-Davies, Australian National University, Canberra, ACT, Australia and B. J. Eggleton, CUDOS, University of Sydney, NSW, Australia We demonstrate coupling to chalcogenide glass based photonic crystal waveguides via tapered microstructured fibre nanowires.

TuZ1 15.30 - 16.00 (Invited)
Engineering Fano Resonances in Photonic Structures with Nonlinear Defects and Cavities, Y. S. Kivshar and A. E. Miroshnichenko, Australian National University, Canberra, ACT, Australia We study linear and nonlinear transmission of photonic structures, such as photonic crystals, nonlinear waveguide arrays, and ring resonators, based on directional waveguides coupled to defects or microcavities. We demonstrate the basic principles of engineering Fano resonances and discuss a novel type of photonic bandgap due to Fano resonances.

TuZ4 16.30 - 16.45
Modal Formulation for Plane Wave Scattering by a Photonic Crystal Slab:
Fano Resonances, L. C. Botten, University of Sydney, Sydney, NSW, Australia, M. Byrne, University of Technology, Sydney, Sydney, NSW, Australia, A. A. Asatryan, University of Sydney, Sydney, NSW, Australia, N. Nicorovici, A. Norton, University of Technology, Sydney, Sydney, NSW, Australia and R. C. McPhedron, University of Sydney, Sydney, NSW, Australia A modal theory of diffraction by planar photonic crystal slabs, based on a multipole-scattering matrix approach, is developed. The theory accurately describes the diffraction problem, providing real insight into the scattering process of Fano resonances.

WA1 08.30 - 09.00 (Invited)
Confinement of Light in Left-Handed Periodic Structures, I. V. Shavidrov, A. A. Sukhorukov and Y. S. Kivshar, Australian National University, Canberra, ACT, Australia We discuss unusual features of wave propagation in periodic arrays of slabs made of transparent left-handed metamaterials with simultaneously negative dielectric permittivity and magnetic permeability, and demonstrate the possibility of light confinement due to the appearance of complete photonic bandgaps in such one-dimensional structures.

WF3 09.00 - 09.15
Slow Gap Soliton Propagation Excited by Microchip Q-Switched Pulses, J. T. Mok, E. Tsoy, I. C. M. Littler, C. M. de Sterke, University of Sydney, Sydney, NSW, Australia and B. J. Eggleton, CUDOS, University of Sydney, NSW, Australia We demonstrate slowly propagating gap solitons excited by microchip Q-switched laser pulses with kilowatts peak power in a 10 cm apodized fibre Bragg grating. Gap solitons propagating at 0.19 c/n are observed.

WA3 09.30 - 09.45
Reduction of Spontaneous Emission in Tapered Photonic Crystal Fibres, J. M. Dawes, S. Myers, Macquarie University, North Ryde, NSW, Australia, D. Fussell, E. Magi, R. C. McPhedron, University of Sydney, Sydney, NSW, Australia, B. J. Eggleton, CUDOS, University of Sydney, NSW, Australia and C. de Sterke, University of Sydney, Sydney, NSW, Australia The spontaneous emission from dye introduced into the centre of tapered hollow-core photonic crystal fibre was characterized in the transverse direction.
Suppression of emission due to local density of state effects, which cannot be understood from the bandstructure alone, were observed to be consistent with theory.

High Performance Bragg Gratings in Chalcogenide Glass Rib Waveguides Written with a Modified Sagnac Interferometer: Fabrication and Characterization, M. Shokooh-Saremi, V. G. Ta’eed, N. J. Baker, CUDOS, University of Sydney, Sydney, NSW, Australia, I. C. M. Littler, D. Moss, University of Sydney, Sydney, NSW, Australia, B. J. Eggleton, CUDOS, University of Sydney, NSW, Australia, Y. Ruan and B. Luther-Davies, Australian National University, Canberra, ACT, Australia We report high performance Bragg gratings in As2S3 chalcogenide glass rib waveguides, written with a modified Sagnac interferometer for the first time. Grating growth dynamics obtained from an in-situ monitoring system are presented and analyzed.

WR2 13.45 - 14.00
All-Optical Directional Coupler Switching in Chalcogenide Glass, Y. Ruan, B. Luther-Davies, A. V. Rode, V. Kolev and W. Z. Krolikowski, Australian National University, Canberra, ACT, Australia The waveguide-based directional couplers in As2S3 glass were fabricated by using inductively coupled plasma (ICP) etching. Their ultrafast all-optical switching operation was demonstrated at 1530 nm with switching peak power of 55 W.

WBB2 15.45 - 16.00
Femtosecond Laser Writing of Symmetric, Low Loss Waveguides in Active Glasses, M. Ams, Macquarie University, North Ryde, NSW, Australia Beam shaping techniques are used to write symmetric, low transmission loss waveguides in bulk media using fs-lasers. The characteristics of waveguides written in active glasses and the implications for miniature waveguide lasers will be presented.

ThM4 11.30 - 11.45
Integrated All-Optical Chalcogenide Waveguide Pulse Regenerator: Experiment and Modeling, V. G. Ta’eed, M. Shokooh-Saremi, CUDOS, University of Sydney, Sydney, NSW, Australia, L. Fu, D. Moss, M. Rochette, I. C. M. Littler, University of Sydney, Sydney, NSW, Australia, B. J. Eggleton, CUDOS, University of Sydney, NSW, Australia, Y. Ruan and B. Luther-Davies, Australian National University, Canberra, ACT, Australia We present an integrated, all-optical, chalcogenide waveguide pulse regenerator based on linear filtering of self phase modulated pulses. We demonstrate a nonlinear transfer function with 1.5 ps optical pulses and find good agreement with theory.

ThM5 11.45 - 12.00
Low Power All-Optical Signal Regeneration in Single Mode As2Se3 Chalcogenide Glass Fiber, L. Fu, M. Rochette, University of Sydney, Sydney, NSW, Australia, V. G. Ta’eed, CUDOS, University of Sydney, Sydney, NSW, Australia, I. C. M. Littler, D. Moss, University of Sydney, Sydney, NSW, Australia and B. J. Eggleton, CUDOS, University of Sydney, NSW, Australia We report low power all-optical signal regeneration in single mode As2Se3 chalcogenide fibre, achieving a near optimum nonlinear power transfer curve with low pulse distortion for 6ps pulses, at <10W peak power.