Development of organic-inorganic optical microcavities for studying polymer thin films

The optical characterization of polymeric materials to understand their fundamental behavior is important to study their materials' properties and to utilize them in numerous applications. Therefore, this thesis mainly investigates the possibilities for the development of hybrid organic-inorganic optical resonators for studying polymer thin films based on whispering-gallery mode (WGM) optical resonators. The long-period light confinement in WGM optical resonators with low loss materials, such as silica, ensures high sensitivity or high quality (Q) factor by scanning optical resonators numerous times, hence extracting the change of information caused in the system during the scan. Such detection mechanisms can be the change of quality factor, resonant shift or transmission change. ❧ In this thesis, it is first demonstrated that the loss mechanism for hybrid optical resonators are material-limited with quality factor over than 10^7, meaning that other loss mechanisms such as scattering, radiation, contamination and coupling losses are minimized with optimized device performance, device fabrication and optical characterization set-up. The change of optical field characterization is also investigated with different polymers, film thickness and operating wavelengths by Finite Element Method (FEM) simulations for the hybrid structure.

为理解聚合物材料的基本特性而开展其光学表征，对于研究该类材料的性能并将其应用于诸多场景具有重要意义。因此，本论文主要探究基于回音壁模式（whispering-gallery mode, WGM）光学谐振器研发混合有机-无机光学谐振器的可行性，以用于聚合物薄膜的相关研究。采用二氧化硅等低损耗材料的WGM光学谐振器可实现长周期光场束缚，通过多次扫描谐振器能够获得高灵敏度或高品质因数（quality factor, Q），进而提取扫描过程中系统内产生的信息变化。此类检测机制可包括品质因数变化、谐振峰偏移或透射率变化。
本论文首先证实，混合光学谐振器的损耗机制受材料本身限制，其品质因数可超过10^7，这意味着通过优化器件性能、制备工艺与光学表征装置，可将散射、辐射、污染及耦合损耗等其他损耗机制降至最低。本论文还通过有限元方法（Finite Element Method, FEM）模拟该混合结构，探究了不同聚合物、薄膜厚度及工作波长下的光场特性变化。