Poled Fibre Devices
Poling is a technique for substantially changing the properties of a material. Typically we apply a very large electric field to silica and then heat or irradiate it. This can induce an electro-optic behaviour in the silica. Devices made from poled silica fibre can be used for electro-optic modulators, electrically tuneable gratings, electric field sensors and a variety of non-linear effects. Research at the University of Sydney has focussed on optimisation of the poling technique, fabrication of suitable fibres, understanding of mechanisms and application of poled fibre.
Our research has contributed substantially to the understanding of the mechanisms in poling. These involve the migration and trapping of charges resulting in an internal space charge field and the enhancement of the third order (Chi3) non-linearity, probably by field-assisted nano-crystallisation. The most notable breakthrough was the dramatic 6pm/V result with UV Poling, which was the first indication that Chi3 change was involved and not just charge migration.
Our research has mostly focussed on the use of Twin Hole Fibre which, whilst more difficult to analyse the smaller active region, has significant benefits due to strong overlaps between the various fields. Recent work has focussed on understanding and optimising the process of Chi3 change and on applications of poled fibre.