Functional Silicon Photonics

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Access to health care is not uniform - many rural and remote communities having only limited access and in low- and middle-income countries the problem can be exasperated buy lack of facilities and trained healthcare workers. The world health organization defines Universal Health Care as: "UHC means that all individuals and communities receive the health services they need without suffering financial hardship. It includes the full spectrum of essential, quality health services, from health promotion to prevention, treatment, rehabilitation, and palliative care across the life course." The use of diverse technologies is key in helping under resourced systems leapfrogging into advanced healthcare systems. Advanced communications, artificial intelligence and big data all have a role to play. In parallel, portable of point-of care testing promises enhanced screening, monitoring and early diagnosis of diseases. Linking together portable sensing systems with robust networks will be necessary. To realize this vision there is a need for low-cost, high performance photonic devices, optical data networks and sensing systems to support a widely accessible internet of things (IoT). Silicon photonics offers a route to achieving low cost and functional integrated optical circuits which can be easily integrated with CMOS electronics and imaging devices. However, as a platform silicon has some limitations. The high refractive index contrast of silicon waveguides results in efficient light confinement within a waveguide and hence poor overlap with the external environment which limits sensing applications. Silicon does not have a direct band gap and hence does not provide optical gain. Silicon has a centrosymmetric crystal structure; hence it does not have a second order nonlinear tensor and no natural electro-optic effect.  This application aims to develop a route towards functional silicon photonics. Our approach will focus on low index waveguide structures and 2D metasurfaces. Waveguides based on the Augmented Low Index Waveguide approach allow for the easy co-integration of transparent materials. We will develop this idea and demonstrate the co-integration of rare earth doped gain materials, nonlinear organics, and functional sensing materials. In parallel, we will work on 2D silicon metasurfaces where we will use stimuli-responsive micro and nano gels to produce optical bio sensors. Our focus will be on blood borne markers available via an easily accessible sample from a finger prick. This program of work will provide an ideal interdisciplinary training ground for graduate students. They will develop skills in photonics, micro and nano-fabrication, and device testing. In parallel we will use this core program to leverage new partnerships with industry, and international collaborators, which will provide students with the opportunities to develop new methodologies and peer networks.