Fibre nanowire sensors

Much effort has been devoted recently to developing compact devices for chemical and biological sensing, in particular for environmental, aerospace and security applications. The double goal is to increase the sensitivity while simultaneously reducing the size of the devices. Here we propose to apply the emerging technology of optical nanowires to this task, which could reduce device sizes from approximately ten centimetres to the sub-millimetre range combined with unprecedented detector sensitivity.Optical nanowires are fabricated from standard optical fibres by a high-temperature drawing process. They have submicron diameters, which allows for easy bending and manipulation, yet they remain relatively strong mechanically. Light propagating in an optical nanowire extends well beyond the material into air, thus providing strong interaction with the environment for sensing applications. Finally, light can easily be coupled into and out of a nanowire, which is important for compact and energy-efficient devices.In this proposal we aim to further develop this emerging technology to reduce transmission losses, to embed nanowires into structural materials for enhanced robustness, and to build self-coupled interferometers and resonators. Finally, we will, for the first time, apply optical nanowires in two specific devices:a) We will manufacture compact high-sensitivity Sagnac interferometers from optical nanowires. Sagnac interferometers are routinely used on aircrafts as rotation sensors. Our new device will be significantly smaller, while providing at least the same sensitivity.b) We will develop a millimetre-sized gas sensor from a partially embedded nanowire resonator. High resonator quality and large interaction of the light with surrounding gas will provide enhanced sensitivity by cavity ringdown spectroscopy.