期刊
SCIENTIFIC REPORTS
卷 4, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/srep07528
关键词
-
资金
- Research Grants Council of the Hong Kong Special Administrative Region, China [618010]
Chip-scale, optical microcavity-based biosensors typically employ an ultra-high-quality microcavity and require a precision wavelength-tunable laser for exciting the cavity resonance. For point-of-care applications, however, such a system based on measurements in the spectral domain is prone to equipment noise and not portable. An alternative microcavity-based biosensor that enables a high sensitivity in an equipment-noise-tolerant and potentially portable system is desirable. Here, we demonstrate the proof-of-concept of such a biosensor using a coupled-resonator optical-waveguide (CROW) on a silicon-on-insulator chip. The sensing scheme is based on measurements in the spatial domain, and only requires exciting the CROW at a fixed wavelength and imaging the out-of-plane elastic light-scattering intensity patterns of the CROW. Based on correlating the light-scattering intensity pattern at a probe wavelength with the light-scattering intensity patterns at the CROW eigenstates, we devise a pattern-recognition algorithm that enables the extraction of a refractive index change, Delta n, applied upon the CROW upper-cladding from a calibrated set of correlation coefficients. Our experiments using an 8-microring CROW covered by NaCl solutions of different concentrations reveal a Delta n of similar to 1.5 X 10(-4) refractive index unit (RIU) and a sensitivity of similar to 752 RIU-1, with a noise-equivalent detection limit of similar to 6 x 10(-6) RIU.
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