NANOPHOTONICS-BASED MID-IR SENSORS

Abstract

Mid-infrared (mid-IR) spectroscopy is a promising technique for non-invasive and label-free molecule identification in various applications such as environmental monitoring, healthcare, clinical diagnosis, and military applications. However, the performance of mid-IR spectroscopy is still limited due to the constraints of the current technology. Plasmonic nanoantennas (PNAs) have emerged as a miniaturized solution for improving the sensitivity and bandwidth of mid-IR spectroscopy. In this thesis, a theoretical framework of loss engineering is proposed to guide the design and optimization of PNAs for sensing applications. Three optimal PNA structures of hook nanoantennas, multi-hotspot nanoantennas, and metal-insulator-metal-based nanorods are investigated to validate the loss engineering approach. Additionally, four platforms, including wavelength-multiplexed hook nanoantennas, polymer/metal-organic-framework integrated multi-hotspot nanoantennas, hybrid nanofluidic-surface-enhanced IR absorption, and hybrid nanofluidic reconfigurable metasurfaces, are developed to demonstrate the potential of PNAs in state-of-the-art gas and liquid sensing applications. Overall, this thesis provides a comprehensive understanding of the design, optimization, and application of PNAs for mid-IR spectroscopy.