Fig. 1. (a) Definition of Dout, Dfiber, and L. (b) Moving a microresonator droplet by using a fiber taper probe. (c) Merging two adjacent droplets into a bigger one. (d) Microscope image of many polymer bottle microresonators with similar shapes. (e) PL intensity and lasing intensity correspond to time when exciting a typical R6G-doped bottle microresonator with power around a lasing threshold. Green dots: initial PL intensity. Orange dots: initial lasing intensity.

Fig. 2. Principle of single WGM lasing in a polymer bottle microresonator. (a) Multimode lasing behavior under uniform pump. (b) Single WGM lasing by adjusting the coupling position to suppress high-order modes.

Fig. 3. (a) Illustration of fiber-taper-coupled bottle microresonator. Definition of DFT is denoted. (b) Microscope image of a polymer bottle microresonator (Dout=5.5  μm, Dfiber=3.2  μm, and L=7.5  μm) coupled with a fiber taper. (c) Emission spectra under fiber-taper-coupled excitation with different pump pulse energy. Inset: dark-field microscope image of the microresonator with Pin=26.1  nJ. (d) Emission intensity of the 603.4 nm wavelength peak versus the pump pulse energy.

Fig. 4. (a) Lasing spectra and (b) their corresponding microscope images of a polymer bottle microresonator (Dout=6.1  μm, Dfiber=3.9  μm, and L=10.8  μm) under uniform and fiber taper coupling pump. (c) Lasing spectra and (d) their corresponding microscope images of another polymer bottle microresonator (Dout=5.3  μm, Dfiber=3.9  μm, and L=7.6  μm) under different diameters of fiber taper coupling pump.

Fig. 5. Electric field-intensity distributions of (a) TM431, (b) TM422, (c) TM423, and (d) TM414 modes, respectively.

Fig. 6. (a) Lasing spectra and (b) their corresponding microscope images of a polymer bottle microresonator (Dout=6.1  μm, Dfiber=3.9  μm, and L=10.8  μm) under uniform and fiber taper coupling pump. (c) Lasing spectra and (d) their corresponding microscope images of another polymer bottle microresonator (Dout=5.3  μm, Dfiber=3.9  μm, and L=7.6  μm) under different diameters of fiber taper coupling pump.