Fig. 1. Schematic diagram of the tapered fiber coupled microsphere cavity

Fig. 2. (a) Resonant spectrum of the microsphere cavity obtained by the finite-difference time-domain method; (b) Whispering gallery mode field distribution at the resonant wavelength 1551.47 nm

Fig. 3. Schematic diagram of the tapered fiber coupled PMMA microsphere cavity packaging process: (a) Placing a low-index rubber gasket on the TEC; (b) Fixing the tapered optical fiber on the gasket; (c) Transferring a PMMA microsphere cavity to the waist of the tapered fiber and then packaging them together by spot curing; (d) Coating and curing the whole device with the low refractive index adhesive

Fig. 4. Schematic diagram of experimental setup for measuring the temperature response of the PMMA microsphere cavity

Fig. 5. (a) Resonant spectrum of the PMMA microsphere with a diameter of 85 μm in the range from 1535 nm to 1565 nm; (b) Resonant spectra of the PMMA microsphere under different temperatures; (c) The details of the spectra around 1559.7 nm in (b); (d) Wavelength shift of the PMMA microsphere with respect to temperature

Fig. 6. (a) Resonant spectrum of the PMMA microsphere with a diameter of 102 μm in the range from 1535 nm to 1565 nm; (b) Resonant spectra of the PMMA microsphere under different temperatures; (c) The details of the spectra around 1560.5 nm in (b); (d) Wavelength shift of the PMMA microsphere with respect to temperature