Microfiber and Microcoil Resonators and Resonant Sensors
The manufacture of tapers from optical fibers provides the possibility to get long, uniform, and robust micrometer- or nanometer-size wires. Optical microfibers are fabricated by adiabatically stretching conventional optical fibers and thus preserve the original optical fiber dimensions at their input/output pigtails, allowing ready splicing to standard fibers. Since microfibers have a size comparable to the wavelength of the light propagating in it, a considerable fraction of power can be located in the evanescent field, outside the microfiber physical boundary. When a microfiber is coiled, the mode propagating in it interferes with itself to give a resonator. In this chapter the latest results on the manufacture of optical microfiber resonators are presented. Optical microfibers can be used to fabricate single-loop and multiple-loop (coil) resonators with extremely high Q factors. High Q resonators can be used for refractometric biosensors and because of their design they provide an exceptionally high sensitivity.
KeywordsFree Spectral Range Fluidic Channel Evanescent Field Leaky Mode Couple Wave Equation
Gilberto Brambilla gratefully acknowledges the Royal Society (London, UK) for his research fellowship. The authors thank EPSRC (UK research council) for financial support.
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