Nonlinear bio nano-sensors via light frequency conversion

促进诊断、药物发现和食品安全的技术对人们的日常生活非常感兴趣和重要。纳米天线生物传感是这些技术的一个重要分支[1-3]。金属纳米天线已被证明是实时检测纳米结构表面发生的生物分子相互作用的通用工具。这种纳米天线已广泛应用于无标签的生物和化学传感。生物化学分子在纳米结构上的存在会导致局部区域b[1]的光学散射发生巨大变化。然而，金属纳米天线吸收大量的光并将其转化为热。这种特性极大地限制了它们的应用，因为它们可能危害生物。另一方面，介电纳米结构由于其低光学损耗和对全功能光子电路的兼容性，引领了纳米光子学的一个新分支[4,5]。通过精心设计电介质光学纳米天线，即使是小体积的生物分子也可以在天线内提供相当大的光学特性变化，这将通过散射场和辐射模式进一步揭示。非线性光学过程允许将电磁辐射转换为不同颜色的光，从而可以提供无背景噪声的传感环境[6]。此外，由于非线性信号对入射光强度的二阶或三阶依赖，非线性光信号使光谱比相应的线性光谱更窄。本项目将非线性纳米光子学与生物传感技术相结合，开发一种基于介电纳米天线的新型非线性生物传感器。通过表征散射场和发射模式的变化，非线性生物传感器将以高灵敏度获取生物样品的详细信息。具体而言，本项目旨在逐步解决以下挑战：1。基于高精细介质光学纳米天线的新一代片上非线性生物传感器的研究。2. 研究被生物分子包围的纳米结构中的光学相互作用，结合新开发的材料，如石墨烯，用于开发下一代单分子传感技术。

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.