Soft Glass and Fibre Fabrication Facility
The optical fibre manufacturing facilities at the Institute for Photonics and Advanced Sensing (IPAS) at The University of Adelaide comprise state-of-the-art fabrication equipment, know-how and capability. This facility in Adelaide forms part of the Australian National Fabrication Facility (ANFF). The ANFF is an eight-node facility, with nodes distributed throughout Australia, drawing on existing infrastructure and expertise.
The OptoFab Node brings together three leading microfabrication groups in NSW, Macquarie University, the University of Sydney, and the Bandwidth Foundry. In February 2009, IPAS joined OptoFab, thus enhancing the optical fibre fabrication capabilities available within the Node.
IPAS has a rare combination of glass science and fibre fabrication research facilities and expertise; which has enabled the realisation of fibres with unique and novel properties.
With expertise spanning the full spectrum of glass materials from silica to soft glasses, IPAS’ internationally leading team in glass extrusion has produced glass fibres with the broadest range of structures, unmatched anywhere else in the world.
Soft glass fabrication
IPAS’ soft glass fabrication facilities support the manufacture of a range of glasses including fluoride, tellurite and germanate. These facilities include equipment for the controlled batching, melting, casting and annealing, which in turn enables production of novel glass compositions, including undoped and doped glasses.
The soft glass production facilities comprise both open-air and controlled-atmosphere glass melting capability. The open-air melting capability consists of a melting furnace with maximum temperature of 1200oC and two annealing furnaces with a maximum temperature of 500oC. The open-air glass melting capability is used to produce a range of tellurite glasses; Na-Zn-La-tellurite glass (undoped or doped with fluorescent rare earth ions) is now routinely made in up to 300g raw material batch sizes.
The controlled-atmosphere glass melting capability consists of a 5-port glove box with integrated melting furnace with a maximum temperature of 800 - 900oC, and an annealing furnace with a maximum temperature of 500oC, and a 6-port controlled atmosphere glove box with one integrated melting furnace and three annealing furnaces.
Soft glass and polymer preform extrusion
IPAS has pioneered methods for extruding glass to form structured preforms. These structured preforms can be produced using soft glass and polymer billets. Preforms can be ultrasonically milled and drilled into a range of cladding shapes as required. These preforms are then drawn down in scale into optical fibres. Fibres can be produced as core-clad and microstructured fibres. A large range of custom, specialised and microstructured fibres can be produced; such microstructured fibres having hole sizes in the range of 20nm - 20µm, with almost arbitrary hole shapes and distributions.
Preforms can be produced with a wide range of structures using soft glass and polymer billets. We currently have 2 extrusion rigs:
Rig 1 can extrude preforms at a temperature of up to 700oC and a force of up to 100kN. Preforms can be made from in-house fabricated glasses and commercially sourced glasses, including: tellurite, bismuth, fluoride (ZBLAN), fluoride-phosphate (Schott: N-FK5, N-FK51A), lead silicate (Schott: LLF1, F2, SF6, SF57) and chalcogenide glasses as well as polymers. The structures can include rods of 1 - 20mm diameter, tubes of 10 - 20mm outer diameter and 0.5 - 8mm inner diameter, wagon-wheel structures (suspended core), hexagonal arrays of 1 - 7 rings of air holes and spider-web like structures with large air filling fractions.
Rig 2 can extrude at forces up to 250kN force and a temperature of up to 1700oC.
Soft glass fibre drawing
A 4m soft glass drawing tower is currently used to draw preforms of 8 - 15mm diameter and up to 180mm lengths into canes of approximately 1mm outer diameter or fibres of 100 - 400µm outer diameter. The temperature range that can be reached in the centre of the hot zone of the RF furnace is approximately 200 - 900oC.
Pressure and vacuum can be applied to the preform during caning and fibre drawing. A range of soft glasses and polymer can be drawn from this tower. In addition, the preform can be spun during fibre drawing. On-line coating of fibres with UV-curable polymer can also be performed.
Glass and fibre characterisation
Additional equipment available within the IPAS glass fibre manufacturing facilities for the characterisation of both soft and silica glass, preforms and fibres include specialised microscopes including a SNOM/AFM.
Scanning Near Field and Atomic Force Microscope (SNOM/AFM)
The SNOM/AFM part can run in collection or transmission mode, and is equipped with an IR detector and an in-built red laser. This equipment is available for both fibre characterisation and other applications.
Glass fibre functionalisation
Surface functionalization takes a material whose surface chemistry is dictated by that material's surface composition and surface properties, and attaches to it specific chemical functional groups, or biochemical functionalities, to impart tailored physical, chemical, or biochemical properties to that material's surface.
For example, a material’s optical properties can be changed, or the introduction of specific functional groups to react in controlled ways with molecules in fluids. It can also include the introduction of receptors for adding chemical or biochemical specificity to a sensor surface. Bulk glass, planar wave guides and fibre surfaces can be functionalised, both internally and externally, allowing the production for example, of novel optical based fibre sensors.
The powerful combination of capabilities available at IPAS, coupled to its competence for synthetic and surface chemistry in the functionalisation of glass fibres, places IPAS in a unique position to offer its surface functionalisation know-how and facilities, to create new fibre-based platform technologies to underpin paradigm-changing tools for human health, the environment, industrial processes and defence systems.
As part of the OptoFab node of the ANFF, IPAS offers a variety of commercial services from the supply of custom glasses and fibres to theoretical modelling and development of novel sensor platforms. Academic groups and companies are encouraged to contact IPAS with their specific requirements or to access our specialised equipment and services.