Bandpass transmission spectra of a whispering-gallery microcavity coupled to an ultrathin fiber

Abstract

Tapered fibers with diameters ranging from 1-4 micron are widely used to excite the whispering-gallery (WG) modes of microcavities. Typically, the transmission spectrum of a WG cavity coupled to a waveguide around a resonance assumes a Lorentzian dip morphology due to resonant absorption of the light within the cavity. In this paper, we demonstrate that the transmission spectra of a WG cavity coupled with an ultrathin fiber (500-700nm) may exhibit both Lorentzian dips and peaks, depending on the gap between the fiber and the microcavity. By considering the large scattering loss of off-resonant light from the fiber within the coupling region, this phenomenon can be attributed to partially resonant light bypassing the lossy scattering region via WG modes, allowing it to be coupled both to and from the cavity, thence manifesting as Lorentzian peaks within the transmission spectra, which implies the system could be implemented within a bandpass filter framework.

4pages,6figures

References in corpus (6)

• A high-Q, ultrathin-walled microbubble resonator for aerostatic pressure sensing
• Coupled-mode induced transparency in aerostatically-tuned microbubble whispering gallery resonators
• Four-wave mixing parametric oscillation and frequency comb generation at visible wavelengths in a silica microbubble resonator
• Tunable erbium-doped microbubble laser fabricated by sol-gel coating
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• Optomechanical Transduction and Characterization of a Silica Microsphere Pendulum via Evanescent Light

Cited by in corpus (3)

• Polarization-Controlled Cavity Input-Output Relations
• Excitation of whispering gallery modes with a "point-and-play", fiber-based, optical nano-antenna
• Repulsive Casimir-Polder potentials of low-lying excited states of a multilevel alkali-metal atom near an optical nanofiber