Fig. 1. DSC curve of as-prepared glass

Fig. 2. XRD patterns of as-prepared glass and PbSe quantum dot (QD)-doped glasses heat-treated at 　different temperatures for 5 h

Fig. 3. Absorption and photoluminescence spectra of as-prepared glass and PbSe QD-doped glasses heat-treated at different temperatures for 5 h. (a) Absorption spectra; (b) photoluminescence (PL) spectra excited by 808 nm laser

Fig. 4. Back scattering images and EPMA analysis of PbSe QD-doped precursor fiber cross-section. (a)Back scattering image of fiber cross-section; (b)(e) EPMA images of different elements in PbSe QD-doped precursor fiber cross-section; (f) partially enlarged back scattering image of fiber cross-section; (g) EPMA line scanning curves of fiber 　along dotted path in Fig.4(f)

Fig. 5. Raman spectra of as-prepared glass and precursor fiber cores, heat-treated PbSe QD-doped glass, and 　PbSe QD-doped glass fiber core and cladding

Fig. 6. TEM image and size distribution of PbSe QD-doped glass fiber after heat treatment. (a) TEM image; (b) size distribution of PbSe QDs in glass fiber

Fig. 7. PL spectra of PbSe QD-doped fiber excited by 808 nm laser. (a) PL spectra of PbSe QD-doped fiber heat-treated at different temperatures for 5 h; (b) PL spectra of fiber heat-treated at 440 ℃ for different durations; (c) variation of PL peak intensity of PbSe QD-doped glass fibers heat-treated at 440 ℃ with fiber length; (d) PL spectra of different 　batches of PbSe QD-doped glass and optical fibers heat-treated at different temperatures

Fig. 8. Optical loss of as-prepared and heat-treated PbSe QD-doped fiber at 1530 nm measured by cutback 　method