Selective excitation of whispering-gallery modes and Fano resonance in a high-Q micro-capillary resonator with cleaned-up spectrum

Abstract

We demonstrate, experimentally and theoretically, a micro-capillary resonator with surface nanoscale axial photonics for clean and nearly equidistant spectra, which belongs to a category of bottle-shaped optofluidic ring resonators. Selective excitation for the lowest five axial modes is achieved by changing the gap between the resonator and the taper and the coupling position along the micro-capillary. By scanning tapered fiber diameters carefully, the resonance state for converting a Lorentzian resonance to a Fano resonance and an electromagnetically induced transparency resonance is exhibited. The results obtained pave the way for an enhanced approach in sensing and, in particular, in microfluidic sensing.

Modulation of Fano-like resonance in spherical microbubble cavity for high sensitivity pressure sensing

“…19) In the experiment, the generation of the Fano line shape requires the superposition of discrete states or continuous states, generally. [20][21][22][23][24] Bo et al realized the coupling of different modes in the optical fiber and the whispering gallery mode in the microsphere resonator by controlling the polarization state of the tapered optical fiber, and then obtained the regulation and control of Fano line shape. 21) Xiao et al obtained the discrete state by introducing another WGM with a higher quality factor into the resonant cavity, 22) While Wu et al used the method of coupling a WGM resonator with a multimode tapered fiber.…”

Notched-elliptical polymer microdisk resonator for unidirectional emission at visible and near-infrared wavelengths

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