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Wireless whispering-gallery-mode sensor for thermal sensing and aerial mapping

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 Added by Xiangyi Xu
 Publication date 2018
  fields Physics
and research's language is English




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Internet of Things (IoT) employs a large number of spatially distributed wireless sen-sors to monitor physical environments, e.g., temperature, humidity, and air pressure, have found wide applications including environmental monitoring, health care monitoring, smart cities and precision agriculture. A wireless sensor can collect, analyze, and transmit measurements of its environment. To date, wireless sensors used in IoT are predominately based on electronic devices that may suffer from electromagnetic interference in many circumstances. Immune to the electromagnetic interference, optical sensors provide a significant advantage in harsh environments. Furthermore, by introducing optical resonance to enhanced light-matter interactions, optical sensors based on resonators exhibit small footprints, extreme sensitivity and versatile functionalities, which can signifi-cantly enhance the capability and flexibility of wireless sensors. Here we provide the first demonstration of a wireless photonic sensor node based on whispering-gallery-mode (WGM) optical resonators. The sensor node is controlled via a customized iOS app. Its per-formance was studied in two practical scenarios: (1) real-time measurement of air tempera-ture over 12 hours and (2) aerial mapping of temperature distribution by a sensor node mounted on an unmanned drone. Our work demonstrates the capability of WGM optical sensors in practical applications and may pave the way for large-scale deployments of WGM sensors in IoT.



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Whispering gallery mode biosensors allow selective unlabelled detection of single proteins and, combined with quantum limited sensitivity, the possibility for noninvasive realtime observation of motor molecule motion. However, to date technical noise sources, most particularly low frequency laser noise, have constrained such applications. Here we introduce a new technique for whispering gallery mode sensing based on direct detection of back-scattered light. This experimentally straightforward technique is immune to frequency noise in principle, and further, acts to suppress thermorefractive noise. We demonstrate 27 dB of frequency noise suppression, eliminating frequency noise as a source of sensitivity degradation and allowing an absolute frequency shift sensitivity of 76 kHz. Our results open a new pathway towards single molecule biophysics experiments and ultrasensitive biosensors.
191 - Y. L. Li , P. F. Barker 2018
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We theoretically study the properties of highly prolate shaped dielectric microresonators. Such resonators sustain whispering gallery modes that exhibit two spatially well separated regions with enhanced field strength. The field per photon on the resonator surface is significantly higher than e.g. for equatorial whispering gallery modes in microsphere resonators with a comparable mode volume. At the same time, the frequency spacing of these modes is much more favorable, so that a tuning range of several free spectral ranges should be attainable. We discuss the possible application of such resonators for cavity quantum electrodynamics experiments with neutral atoms and reveal distinct advantages with respect to existing concepts.
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