In Hollow Core Fibres, the signal-bearing light is almost entirely restricted to the central hollow void. The removal of glass from the core dramatically reduces impairments which arise from light-dielectric interaction in conventional fibres – non-linear effects, Rayleigh scattering, and environmental sensitivities are all reduced – most by several orders of magnitude. With such improvements, Hollow Core Fibres are becoming a powerful enabling platform for ultra-high-performance interferometric and resonant sensing applications, in which freedom from distortion and signal purity are the paramount concerns.
One such ultra-precision interferometer is the Fiber-Optic Gyroscope (FOG), a device which measures rotation optically via the Sagnac Effect. FOGs are one of the most successful fibre sensors in history, and a vital technology for guidance and navigation systems. At the heart of this sensor is a long - sometimes multi-kilometre – fiber which is coiled into the size of a teacup or smaller. FOGs are among the most demanding applications of a fibre sensor, both due to their extreme performance needs, and because they are used to navigate vehicles in the most severe environments known to man: from submarines in the depths of the ocean, to satellites and shuttles in the vacuum of space. As FOGs must endure these harsh environments for decades-long missions the fibre must be exceptionally robust and reliable.
Our group works to develop the HCFs which will push the performance envelope in the next generation of FOGs and like sensors. We examine HCF guidance properties in severe deployment conditions and evaluate environmental and lifetime effects. Further, we have developed a suite of tools and advanced characterisation techniques for the study of polarization and spatial mode propagation in HCFs – crucial characteristics for FOG performance. Along with these measurements of fundamental properties, we are also exploring new sensor architectures which are enabled by the unique properties of HCFs.