We present a cascaded side-coupled silicon-on-insulator (SOI) photonic crystal nanobeam cavities (PCNCs) sensor for simultaneous sensing of the refractive index (RI) and temperature. Two types of PCNCs are designed for increasing the demodulation coefficient: the low-index mode cavity exposed to water directly (${{\rm cav}_1}$) and the high-index mode cavity covered with SU-8 cladding (${{\rm cav}_2}$). Moreover, the cascaded side-coupled system is modeled, and the transmission expression is derived based on temporal coupled-mode theory. Furthermore, the correlations between the structural parameters, the transmission, quality factor are discussed. By using three-dimensional finite-difference time-domain simulations, we further prove the ability to detect RI and temperature simultaneously, obtaining a RI sensitivity of 210 nm/RI unit (RIU) and a temperature sensitivity of 53 pm/K for ${{\rm cav}_1}$, whereas there is a RI sensitivity of 0 nm/RIU and a temperature sensitivity of ${-}{90}\;{\rm pm/K}$ for ${{\rm cav}_2}$. Moreover, the maximum of external interference ranges of the proposed sensor are ${7.5} \times {{10}^{- 6}}$ and 0.01 for the RI and temperature, respectively, and the deviation ratios are approximately 0.56% and 3.33% for the RI and temperature, respectively. Therefore, the proposed sensor has strong anti-interference ability and accuracy, which is a promising platform for future applications of dual-parameter sensing.

中文翻译：

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基于级联侧耦合光子晶体纳米束腔的抗外部干扰传感器，可同时检测折射率和温度

我们提出了一种级联的侧耦合绝缘体上硅（SOI）光子晶体纳米束腔（PCNCs）传感器，用于同时感测折射率（RI）和温度。设计了两种类型的PCNC来增加解调系数：直接暴露于水的低折射率模腔（$ {{\ rm cav} _1} $）和覆盖有SU-8包层的高折射率模腔（$ { {\ rm cav} _2} $）。此外，对级联侧耦合系统进行建模，并基于时间耦合模式理论推导传输表达式。此外，还讨论了结构参数，透射率，品质因数之间的相关性。通过使用三维有限差分时域仿真，我们进一步证明了同时检测RI和温度的能力，获得$ {{}的RI灵敏度为210 nm / RI单位（RIU），温度灵敏度为53 pm / K。{\ rm cav} _1} $，而RI灵敏度为0 nm / RIU，温度灵敏度为$ {-} {90} \; {\ rm pm / K} $对于$ {{\ rm cav} _2} $。此外，建议的传感器的最大外部干扰范围为$ {7.5} \ times {{10} ^ {-6}} $RI和温度分别为0.01和0.01，而RI和温度的偏离率分别约为0.56％和3.33％。因此，所提出的传感器具有很强的抗干扰能力和精度，为双参数传感的未来应用提供了有希望的平台。