We propose a new type of self-referencing and multiplexed refractive index (RI) sensor based on a compound optical microresonator structure consisting of Fabry-Pérot (FP) resonators coupled with microring resonators. The transmission spectra shows resonant features that are superimposed on a background defined by FP oscillations. The resonances have asymmetric Fano-like non-Lorentzian shapes, which are used as sensing peaks, while the FP oscillations are used as reference peaks for internal self-referencing. The sensing peaks shift linearly with the increased RI of the cladding in the microring resonator, while FP peaks stay constant. When the temperature is increased, both the FP peaks and the Fano resonances shift linearly at the same rate, which eliminates the temperature effect on RI measurements. We theoretically analyzed that the two-mirror FP resonator coupled with a single microring resonator and optimized its sensing performance through finite-difference time-domain simulations. A sensitivity value of 220 nm/RIU and a maximum figure of merit of 4400 RIU^-1 were achieved. We also proposed two possible multiplexing schemes consisting of two-mirror and three-mirror FP resonators coupled with two microring resonators of different radii. The proposed sensor concept is simple, easy-to-fabricate, self-calibrating and can be used for simultaneous measurements of different samples.

中文翻译：

---

用于自参考和复用折射率传感的复合光学微谐振器设计

我们提出了一种基于复合光学微谐振器结构的新型自参考和复用折射率 (RI) 传感器，该结构由与微环谐振器耦合的法布里-珀罗 (FP) 谐振器组成。透射光谱显示了叠加在由 FP 振荡定义的背景上的共振特征。共振具有不对称的类 Fano 非洛伦兹形状，用作传感峰，而 FP 振荡用作内部自参考的参考峰。传感峰值随着微环谐振器中包层 RI 的增加而线性移动，而 FP 峰值保持不变。当温度升高时，FP 峰和 Fano 共振以相同的速率线性移动，这消除了温度对 RI 测量的影响。我们从理论上分析了双镜 FP 谐振器与单个微环谐振器的耦合，并通过有限差分时域仿真优化了其传感性能。灵敏度值为 220 nm/RIU，最大品质因数为 4400 RIU^-1达到了。我们还提出了两种可能的复用方案，由两镜和三镜 FP 谐振器与两个不同半径的微环谐振器组成。所提出的传感器概念简单、易于制造、自校准，可用于同时测量不同样品。