Refractometry with Ultralow Detection Limit Using Anisotropic Whispering-Gallery-Mode Resonators

W. Weng, James Anstie, Andre Luiten

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    10 Citations (Scopus)

    Abstract

    © 2015 American Physical Society. The intrinsic sensitivity of whispering-gallery-mode resonators aimed at measuring refractive index can be extremely high, although their practical performance is compromised by temperature fluctuations that masquerade as refractive-index changes. We present a triple-mode approach that delivers simultaneous and independent sensing of temperature and refractive-index changes in the same resonator. The frequency difference between two orthogonally polarized modes is used to sense temperature which is then actively stabilized to ∼1 μK over 15 minutes. We then detect a frequency difference between two modes of different wavelengths to obtain a refractive-index measurement that is free of temperature fluctuations. This triple-mode technique delivers a state-of-the-art detection limit of 8×10-9 refractive-index units, despite the resonator size being 100 times larger than that typically used for sensitive refractometric sensing.
    Original languageEnglish
    Article number044015
    JournalPhysical Review Applied
    Volume3
    Issue number4
    DOIs
    Publication statusPublished - 24 Apr 2015

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