Liquid microdroplets have a spherical geometry, smooth surface, and their size and shape can be easily tuned. These properties make them ideally suited for many optical applications. However, microdroplets have up to date found only a limited use, mainly due to the difficulty in their position stabilization. Traditional position stabilization techniques such as electrodynamic levitation, optical levitation, and optical tweezing suffer from fragility and do not allow integration with other optoelectronic components. Superhydrophobic supporting surfaces provide a natural solution to this critical problem. In addition to preserving the spherical geometry of microdroplets of water and other hydrophilic liquids, they provide a highly robust position stabilization mechanism and allow interfacing with other necessary components of integrated lab-on-a-chip systems. The main scientific objective of the proposed research project is the exploration of the intriguing optical properties of surface-supported liquid microdroplets that can act as ultrahigh-quality tunable optical microcavities. Using tapered fiber coupling of a tunable-wavelength laser light into the droplets, we will explore their ultrahigh-quality optical modes for various combinations of droplet size, shape, and refractive index. We will build upon the existing expertise that has already been obtained in the host laboratory and extend the fundamental knowledge that is crucial for applications of supported microdroplets in integrated optofluidic systems. Subsequently, we will also investigate the potential of microdroplet-based resonant cavities for molecular sensing applications. We expect that our results will pave way for practical utilization of microdroplets as highly-flexible micro-optical components of integrated lab-on-a-chip systems in a variety of research fields, e.g. quantum and nonlinear optics, aerosol physics and chemistry, and chemical and biological sensing.