Internally-tuning whispering-gallery modes in a high-Q conical microresonator for electromagnetically induced transparency-like effect

In this study, we experimentally and theoretically demonstrate electromagnetically induced transparency (EIT)like in a single conical microresonator (CMR) fabricated by combining arc discharge and pull method. Benefited from the gradually changing diameter along the longitudinal axis of the CMR, the resonance frequency can be tuned when the CMR coupled by a tapered fiber waveguide. The characteristic of internally-tuning in our CMR is confirmed theoretically, numerically and experimentally. In particular, Fano and EIT-like effect with a quality (Q) factor are achieved by scanning the varied diameter carefully originating from approximate two resonant frequencies in a wavelength apart. In addition, these experimental observations can be well fitted with the coupled mode theory. These findings may open new avenues for realizing high-Q EIT, which pave the way for an enhanced approach in bio-sensing applications, nonlinear optics and optical switching devices.

Automated summary

This study experimentally and theoretically demonstrates electromagnetically induced transparency (EIT)-like effect in a single conical microresonator (CMR). By tuning the diameter of the CMR, the resonance frequency can be controlled. The achieved Fano and EIT-like effects show the potential of the CMR in high-Q EIT and applications in bio-sensing, nonlinear optics, and optical switching devices.