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Micro-ring resonators have been widely employed, in recent years, as wavelength filters, switches and frequency converters in optical communication circuits, but can also be successfully used as transducing elements in optical sensing and biosensing. Their operation is based on the optical coupling between a ring-shaped waveguide and one or more linear waveguides patterned on a planar surface, typically an input and an output waveguide. When incoming light has a wavelength which satisfies the resonance conditions, it couples into the micro-ring and continuously re-circulates within it. A fraction of this resonant light escapes the micro-ring structure and couples into the output waveguide. The presence of a target analyte over the top surface of the micro-ring (i.e. within the evanescent field) changes the effective refractive index of the mode propagating into the structure, thus causing a shift in resonance …
International Society for Optics and Photonics
Publication date: 
18 May 2009
Biblio References: 
Volume: 7356 Pages: 735603
Optical Sensors 2009