Fig. 1. Rare earth ion doped glass ceramic fibers fabricated by double-crucible method[14,16]. (a) Schematic of double-crucible method; (b) (c) emission spectra of fiber and glass ceramic fiber fabricated by double-crucible method; (d) laser slope curves of fiber and glass ceramic fiber; (e) X-ray diffraction (XRD) pattern of glass ceramic fiber

Fig. 2. Rare earth ion doped glass ceramic fibers fabricated by melt-in-tube method[17-18]. (a) Schematic of melt-in-tube method; (b) XRD of fibers and glass ceramic fibers (0 ℃ indicates the non heat treated fiber.); (c) mid-infrared emission spectra; (d) transmission electron microscopy (TEM) image; (e) high resolution transmission electron microscopy(HRTEM)image; (f) photo of fiber cross section; (g) upconversion emission spectra

Fig. 3. Transition metal ion doped glass ceramic fibers fabricated by melt-in-tube and rod-in-tube methods[21-22]. (a)(b) Photos of glass rod before and after drawing process by rod-in-tube method; fibers and glass ceramic fibers by melt-in-tube method for (c) TEM image, (d) Raman spectra, (e) near-infrared mission spectrum of Ni2+, (f) XRD patterns, (g) visible emission spectrum of Cr3+

Fig. 4. PbS quantum dots doped glass ceramic fibers fabricated by melt-in-tube method at high temperature[30]. (a) Photo of preform; (b) photo of fibers; PbS quantum dots doped fibers for (c) TEM image, (d) HRTEM image, (e) Raman spectra, (f) emission spectra

Fig. 5. PbS quantum dots doped glass ceramic fibers fabricated by melt-in-tube method at low temperature[31]. (a) Photo of cross section of fiber; (b)-(h) element distribution patterns of fiber cross section; (i) thermal expansion coefficient curves of glasses; (j) emission spectra of fibers at different temperatures

Fig. 6. SHG glass ceramic fibers fabricated by melt-in-tube and rod-in-tube methods[33]. (a) Photo of glass rod drawn by rod-in-tube method; fibers and SHG fibers fabricated by melt-in-tube method for (b) cross section image, (c) Raman spectra, (d) emission spectra