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Optical Device Fabrication

Photonic chips containing high performance nonlinear optical processing devices are required for future telecommunications networks and all-optical processors. We are developing of novel photonic chips based on chalcogenide glasses that offer the possibility of on-chip all-optical processing. Both conventional waveguide structure and photonic crystal structures are being developed. The challenge lies in the identification of materials suitable for chip fabrication; the design of the photonic structure; structure fabrication and device testing. Processing methods include conventional fine line lithography with nanoscale structures produced by a focused ion beam mill. The work is carried out in collaboration with the ARC Centre of Excellence in Ultra-high Bandwidth Devices for Optical Systems

Chalcogenide Waveguide

Chalcogenide glasses comprise a wide range of amorphous materials containing the chalcogen elements S, Se and Te compounded with network forming elements such as As, Ge, Si, etc. We have chosen these materials because they have high refractive index, large third order nonlinearity, and good photosensitivity whilst being free of absorption across the whole of the near- and mid-infra-red. A challenge with chalcogenides arises from their relatively weak chemical bonding. This results in low melting temperatures and structural instability, leading to a range of exotic phenomena such as quasi-crystallization and enhanced photosensitivity even at wavelengths well beyond their band edge.

Prof. Barry Luther Davies; Dr Steve Madden; Dr Duk Yong Choi; Dr Andrei Rode; Dr Douglas Bulla; Ms Anita Smith; Mrs Maryla Krolikowska ; Amrita Prasad; Darren Freeman;

Photonic Crystal

Photonic crystals are usually viewed as an optical analog of semiconductors that modify the properties of light similarly to a microscopic atomic lattice that creates a semiconductor band-gap for electrons. It is therefore believed that by replacing relatively slow electrons with photons as the carriers of information, the speed and band-width of advanced communication systems will be dramatically increased, thus revolutionizing the telecommunication industry. Fabrication of photonic crystal is one of the greatest challenge of current photonic research.

Highlight article: Chalcogenide Glasses Reveal the Hole Picture

Prof. Barry Luther Davies; Dr Steve Madden; Darren Freeman;

Tellurite Waveguide

Tellurite glasses are broad class of multi-components oxide glasses containing predominantly Tellurium Oxide (TeO2). Tellurite glasses are promising for a wide range of applications of generating mid-infrared light for sensing, spectroscopy, telecommunications. Important optical properties of Tellurite include: being a very good hosts for rare earth ions (Erbium, Thulium etc which can be used for laser amplifier), having high Raman gain coefficient (30-60 times higher than silica) and Raman shift at about double that of silica. Furthermore, Tellurite glasses can be poled to achieve second order nonlinearities with coefficient comparable with those of crystalline materials. This property can be used for electro-optic devices or frequency conversion via parametric mixing. Tellurite glasses have also been recognised for its third order nonlinearity as having the largest coefficient between oxide based glasses. Because they have band edge at very short wavelength, 300-400nm, they also can handle very high optical intensity without the multi-photon absorption and photo darkening that affect most of current materials currently used for thin film optical applications.

Dr Steve Madden; Prof. Barry Luther Davies; Khu Vu; Dr Douglas Bulla;