Nanophotonics is the science that studies photonics at the nanoscale and promises solutions to the biggest challenges in information and communication technologies (ICTs): In the past century, long-distance data transmission was revolutionized by photonics through the use of optical fibres. Today, the communication bottleneck lies on the switching and routing of signals in data centres, which still depend on electronic processing in microelectronic-based switches and routers, with low bandwidth and high energy consumption and residual heat. The ICT sector including data centres generates up to 2% of the global CO2 emissions, a number on par to the aviation sector contribution, and data centres are estimated to have the fastest growing carbon footprint from across the whole ICT sector, due to the rapid growth of the use of Internet services. Nanophotonics can provide a platform for all-optical switching and routing in integrated optical interconnects, with a huge boost in bandwidth, and importantly, a greatly reduced power consumption, of great environmental and economic importance. Ultrafast light routing at the nanoscale is thus a big current challenge with high potential impact.
Near-field directionality of light, being researched in the PSINFONI project, can provide a fundamental solution to the ultrafast routing challenge described above. In essence, the polarization of light or polarization of a light source may affect light's propagation direction. Hence, all-optical ultrafast switching on light polarization can be used for light switching and routing, without relying on electronics. The inverse scenario suggests the possibility of integrated nano-photonic light polarimeters based on this robust electromagnetic phenomenon. PSINFONI will theoretically and experimentally explore the basic science and potential for devices using these phenomena.
Nanophotonics has also been an enabling technology for advancements in other sciences via the possibility of optical tweezers and optical forces, which received the 2018 Nobel prize in Physics. Researchers in the biological and healthcare sciences, among others, greatly benefit from the possibility of utilizing optical forces to trap, move and manipulate small molecules or even living cells. However, these tools require complex setups to achieve the focusing of a laser beam into very tight volumes to create the optical trap, and subsequent movement of that focus. This allows for movement of one single optical trap at a time, but a massively-parallel movement of several molecules, particles or cells is not easily scalable. The PSINFONI project aims to explore the possibility of achieving optical forces for the manipulation and movement of particles without using focused illumination, instead relying on the particle-surface interactions that occur in the near field when particles close to a surface are illuminated using a simple plane wave, which can then be controlled via the illuminating light polarization. The use of plane waves for optical forces would allow massively-parallel control, movement and/or sorting of vast numbers of particles simultaneously. We also explore the regime of Casimir forces, when no illumination is involved.
Both the near-field directionality of light, and the repulsive and lateral optical forces on particles under plane wave illumination, rely on the near field interactions of polarized particles with a nearby surface or waveguide. The PSINFONI project relies on our expert in-depth knowledge of these near-field particle-surface interactions, allowing us to efficiently explore the space of achievable possibilities in the ideas described above.
