Light is a key driver for several fundamentally important processes in the ocean including ocean warming, photosynthesis and animal behaviour. Together, these processes play vital roles in establishing the contribution of the ocean to climate change and how ocean biology will respond to a warming planet. The oceans present an extremely harsh environment that limits our ability to adequately monitor these processes. Optical sensing is particularly well suited for marine monitoring applications for a variety of practical reasons and there is growing interest in developing new sensing technologies that will allow us to better exploit the opportunities offered by the development of autonomous sampling platforms.  

The advent of quantum technology and continued advances in photonics are opening the door to new sensing opportunities in the marine environment. This project will look at deploying integrated quantum technologies in a series of ocean data sensor demonstrations that will showcase some of the new possibilities that are now possible.  

The first application involves using state of the art solid state detectors to develop ultra-high dynamic range irradiance sensors that will enable passive measurement of underwater light fields from noontime daylight to the middle of polar night and down to the darkest levels found at abyssal depths. Seamlessly moving from daytime sensing to photon counting in the dark, this radically new light sensor will provide genuinely global coverage of underwater light signals across the full range of biological sensitivity.  

This ultra-high dynamic range sensing capability has other immediate applications in marine sensing. Light is attenuated exponentially as it passes through turbid media, with LIDAR signals experiencing double attenuation before being received by the detector. The ultra-high dynamic range, high-speed, light sensor will provide new capabilities to extend the sensitivity range for quantum LIDAR systems, including both to greater distances where signals are weak and near field signals that are often ecologically important, but too intense to be measured with systems that are optimised for maximum depth penetration.  

Finally, the project will exploit the exquisite sensitivity and time of flight precision that single photon detection provides to develop new spectroscopic sensors that will facilitate clear discrimination of Raman and other inelastic scattering signals. This will provide new capabilities to determine particle composition with tremendous potential to discriminate between organic, inorganic and anthropogenic materials, including microplastics and oil droplets.