We present a comprehensive overview of sensor technology exploiting optical whispering gallery mode (WGM) resonances. After a short introduction we begin by detailing the fundamental principles and theory of WGMs in optical microcavities and the transduction mechanisms frequently employed for sensing purposes. Key recent theoretical contributions to the modeling and analysis of WGM systems are highlighted. Subsequently we review the state of the art of WGM sensors by outlining efforts made to date to improve current detection limits. Proposals in this vein are numerous and range, for example, from plasmonic enhancements and active cavities to hybrid optomechanical sensors, which are already working in the shot noise limited regime. In parallel to furthering WGM sensitivity, efforts to improve the time resolution are beginning to emerge. We therefore summarize the techniques being pursued in this vein. Ultimately WGM sensors aim for real-world applications, such as measurements of force and temperature, or alternatively gas and biosensing. Each such application is thus reviewed in turn, and important achievements are discussed. Finally, we adopt a more forward-looking perspective and discuss the outlook of WGM sensors within both a physical and biological context and consider how they may yet push the detection envelope further.

中文翻译：

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耳语画廊模式传感器

我们全面概述了利用光学回音壁模式 (WGM) 共振的传感器技术。在简短介绍之后，我们首先详细介绍光学微腔中 WGM 的基本原理和理论，以及经常用于传感目的的转导机制。重点介绍了近期对 WGM 系统建模和分析的主要理论贡献。随后，我们通过概述迄今为止为提高当前检测限所做的努力，回顾了 WGM 传感器的最新技术。这方面的建议很多，范围广泛，例如，从等离子体增强和有源腔到混合光机械传感器，这些传感器已经在散粒噪声限制范围内工作。在提高 WGM 敏感性的同时，开始出现提高时间分辨率的努力。因此，我们总结了在这方面所追求的技术。最终，WGM 传感器的目标是现实世界的应用，例如力和温度的测量，或者气体和生物传感。因此依次审查每个此类应用程序，并讨论重要的成就。最后，我们采用更具前瞻性的视角，在物理和生物环境中讨论 WGM 传感器的前景，并考虑它们如何进一步推动检测范围。