Fig. 1. Several oxide glass microspheres. (a) SiO2 glass microsphere; (b) tellurite glass microsphere; (c) phosphate glass microsphere; (d) germanate glass microsphere

Fig. 2. Fabrication process of microsphere. (a) Diagram of the microsphere fabrication process; (b) microsphere cavity prepared by ZBLAN fiber (the picture is processed optimization)

Fig. 3. Microsphere fabrication process of the three-step method. (a) Taper with 15-μm waist; (b) bulge formed by shearing optical fiber near the waist of taper; (c) As2Se3 glass microsphere formed by thermal melting at bluge

Fig. 4. Microspheres prepared by sol-gel method. (a) Undoped SiO2 microsphere; (b) solution-coated SiO2 microsphere; (c) Yb3+-Ho3+ co-doped microsphere formed by re-melting

Fig. 5. Microspheres fabricated by powder floating method. (a)Tellurite glass microspheres; (b) chalcogenide glass microspheres

Fig. 6. Laser and nonlinear effect in silica microspheres. (a) Laser output power versus absorbed pump power in the microsphere laser. The inset shows the spectrum of the microsphere laser; (b) spectrum of a 70-μm-diameter silica microsphere laser with 2-mW pump power at 1555 nm. The inset shows a microsphere coupled to a fiber taper