Nonlinear bio nano-sensors via light frequency conversion

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Technologies facilitating diagnostics, drug discovery, and food safety are of great interest and importance to people's daily lives. Biosensing via nanoscale antennas is one important branch of these technologies [1-3]. Metallic nanoantennas have been proved as versatile tools for detecting biomolecular interactions occurring at the nanostrucures' surface in real-time. Such nanoantennas have been widely used for label-free biological and chemical sensing. The presence of bio-chemical molecules on nanostructures can lead to a dramatic change in the optical scattering of the local area [1]. However, metallic nanoantennas absorb a large amount of light and convert it to heat. Such a characteristic significantly restrict their applications, as they may harm the living organisms. Dielectric nanostructures, on the other hand, lead a new branch of nanophotonics due to their low optical losses and their compatibility for full-functional photonic circuitry [4,5]. By carefully designing dielectric optical nanoantennas, even small volumes of biological molecules can provide a sizeable change in the optical properties within the antenna, which will be further revealed by the scattered fields and radiation patterns.The nonlinear optical process allows converting electromagnetic radiation to a different colour of light, thus can provide a background-noise-free sensing environment [6]. Furthermore, the nonlinear optical signal enables a narrower spectrum than the corresponding linear light spectrum due to the second- or third-order dependence of the nonlinear signal on the incident light intensity. This project will combine nonlinear nanophotonics with biosensing technology to develop a new type of nonlinear biosensors based on dielectric nanoantennas. By characterising the scattered field and emission pattern variations, the nonlinear biosensors will retrieve detailed information about the biological sample with high sensitivity.Specifically, this project aims to address the following challenges step by step:1. Develop a new generation of on-chip nonlinear biosensors with enhanced performance based on high-finesse dielectric optical nanoantennas. 2. Investigate optical interactions in nanostructures surrounded by biological molecules, integrated with newly developed materials, such as graphene, for developing next-generation single-molecule sensing techniques.