Fig. 1. (a) Method to fabricate the fiber bottle microresonator. The fiber is heated by a CO2 laser to make two microtapers at positions A and B under the pull of the gravity. Then they will form a bottle microresonator. (b) The bottle resonator studied in the experiment. The long horizontal line is the fiber taper.

Fig. 2. Transmission spectrum of the bottle resonator.

Fig. 3. Experimental transmission spectra and theoretical fittings from the dynamic equation. The zero time is set to be the moment that the instantaneous frequency of the laser equals the resonance frequency of the mode. (a) A ringing phenomenon is observed with a fast laser sweeping speed of 56.81 nm/s. (b) Transmission spectrum with a lower laser sweeping speed of 2.91 nm/s.

Fig. 4. (a) The observed ringing spectrum and the new theoretical fitting with the function in Eq. (5) describing the light in the resonator. The zero time is set to be the moment that the instantaneous frequency of the laser equals the resonance frequency of the mode. (b) Comparison of the light field intensity in the resonator predicted by the two theories. The result from the dynamic equation (blue line) shows that there will be an oscillation.

Fig. 5. Comparison of the real and the imaginary parts of 2keEc′(t)/Ein(t) and 2keEc(t)/Ein(t) in (a) and (b), respectively. It can be seen that the real parts agree very well. The zero time is set to be the moment that the instantaneous frequency of the laser equals the resonance frequency of the mode.