Strain-induced tunable dual-bottle-shaped optical microresonator

We present a novel dual-bottle microresonator with a high Q-factor exceeding 10⁷. Such a resonator consists of two lateral resonators and one central resonator. The maximum diameter of the lateral resonator is ∼ 180 µm, and the central diameter is 124.91 µm. Characteristics of the whispering gallery mode spectra are investigated and explained by the microbottle resonance, mode interference, and scattering effects. Strain-tuning sensitivity varies from 0.126 to 1.7 pm/µε when a tapered fiber is placed at the resonator’s different positions. With a coupled area at the middle of the central resonator, the highest, to the best of our knowledge, strain sensitivity of 1.7 pm/µε, which is higher than previously reported solid microresonator strain sensors, is achieved.