Sensing with structured beams

The drive for high-bandwidth, secure communications links has led to space-division-multiplexing (SDM) becoming a burgeoning area of study, where multiplexing independent spatial channels can act to increase the capacity of communication links. SDM techniques implemented in systems employing both optical and radiofrequency carriers have recently received interest from the community for use within point-to-point communication links, particularly in long distance fibre links [1– 3]. Many of these studies have driven the development of tools and technologies for the efficient collection and processing of the light carrying spatial information that can be repurposed for novel sensing applications. Localised heating, suspended particles, turbidity and mechanical mixing, such as moving air or flowing water, all result in degradation of the optical field [4, 6]. The specific degradation that occurs over the channel can reveal important information about the physical properties of the environment the beam have propagated through.