Date of Award
Doctor of Philosophy (PhD)
Whispering-gallery mode (WGM) optical microresonators have been used in various scientific disciplines ranging from fundamental science to engineering applications due to their significantly enhanced light-matter interactions enabled by their high-quality factor and micro-scale mode volume. For example, relying on measuring either shifting, splitting, or broadening of the resonance mode, researchers used WGM microresonators as excellent platforms for sensing applications, including bio-sensing, temperature sensing, magnetic sensing, and so forth. Currently, WGM microresonators are mainly manufactured from traditional materials such as silica, silicon, silicon nitride, and rare-earth-doped glass with state-of-art technologies. However, recent developments in photonics technologies have shown strong demand for developing soft optical devices and photonic structures for bio-photonics applications. As a kind of biopolymer originating from nature, silk materials with their excellent mechanical, optical, and biomedical properties may not only address the needs for desired applications but also enable new applications where biocompatibility is required. In this dissertation, I present the fabrication, characterization, and applications of high-Q WGM optical microresonators made of silk materials. First of all, for the first time on record, I demonstrated high-Q silk microtoroid WGM resonators with a quality factor on the order of 105 via the soft lithography method. The results support that silk microtoroid WGM resonators have a thermal response of 1.17nm/K, one of the highest records among WGM optical resonators based thermal sensors. Besides, I used silk microtoroid resonators to investigate the cavity-enhanced Raman scattering using WGM resonators. The validations of silk microtoroid resonator and silk fiber in optical communication such as add-drop filter and waveguide are also presented. To surpass the limit of silk microtoroid optical microresonators, we reported the first silk microbottle resonators with a quality factor of 10^5 using additive manufacturing. The statistical results indicate that silk microbottle manufactured in this method has consistently achieved quality factor in the range of 3x10^5. A demonstration of humidity response using silk microbottle WGM resonators was also given. As the last focus of this dissertation, I presented the packaged silk microbottle resonators for applications such as UV sensing, imaging, and pulse detection. The results showed that the UV response of packaged silk microbottle resonators (MBR) is about five times higher than the previous UV sensors using silica WGM resonators. I also validated the applications of imaging and pulse detection using packaged silk MBR. The pulse response of packaged silk MBR was about ten times larger than packaged silica WGM resonators. Besides, a portable system integrated with packaged silk WGM microresonators for the Internet-of-Things technology was also presented.
Harold Li, Srikanth Singamaneni, Chuan Wang, Fuzhong Zhang,
Available for download on Thursday, January 10, 2041
Electrical and Electronics Commons, Materials Science and Engineering Commons, Mechanics of Materials Commons, Optics Commons