The characteristics of a microring resonator in optical waveguide displacement sensors

作者：Zhe Ji, Yunxiang Yan, B H Wang, Guoqing Jiang, S B Yan, Wendong Zhang · 发表于：Proceedings of the Institution of Mechanical Engineers Part N Journal of Nanoengineering and Nanosystems · 年份：2008 · DOI：10.1243/17403499jnn152 · 研究领域：Photonic and Optical Devices、Advanced Fiber Laser Technologies、Mechanical and Optical Resonators

Pumping a single-mode, tunable, external-cavity laser to excite the whispering gallery modes (WGM) of microring resonators (MRRs) allows the observation of a series of equidistant, wide free spectrum ranges (FSR). A frequency shift of an FSR can be used to feedback external changes, making MRRs very promising for high-sensitivity sensing. Furthermore, sensor performance is intimately related to the resonance condition and resonator quality factor, Q. In this paper, a novel displacement sensor composed of a microring resonator and a waveguide is presented. Materials selection is discussed. The two most important influencing factors, the optimized resonance condition and Q, are demonstrated especially. Based on mathematical analysis and finite-difference time-domain simulation, the optimized resonance is obtained when the radius and coupling distance are around 20μ and 0.2μ, respectively, with the FSR of the transmission spectrum about 13.6nm. Correspondingly, the ultimate Q is approximately 10 2 in the preliminary experiment.