Fig. 1. Comparison between PbSe-QDF and conventional SiO2 single mode fiber

Fig. 2. TEM images of PbSe quantum dot doped glass fiber under different scales. (a) 20 nm; (b) 5 nm; (c) 2 nm

Fig. 3. Particle-size distribution of PbSe QDs in fiber samples

Fig. 4. Level-transition diagram of PbSe QDs

Fig. 5. Absorption-emission spectra of PbSe-QDF

Fig. 6. Measured pump power versus fiber length

Fig. 7. PL spectra of QDF. (a) PL intensity of QDF versus fiber length under different annealing conditions; (b) PL intensity spectral distribution under different fiber lengths

Fig. 8. Comparison of PL spectra of the identical QDF. (a) Initial time; (b) one month later

Fig. 9. Experimental setup of QDFA

Fig. 10. Spectral distribution of QDFA output signal under different pump powers. The illustration is output spectrum for zero pump

Fig. 11. Homogeneity of the output signal gain of QDFA

Fig. 12. Variation curves of switching gain of QDFA under different pump powers

Fig. 13. Signal gain versus pump power, where the illustration is partial magnification. (a) QDFA in this paper (switching gain for Pi≈-17 dBm); (b) QDFAevan(Pi≈-63 dBm)[10] and FMEDFA (Pi≈-10 dBm)[13]

Fig. 14. Gain and noise spectra of QDFA

Fig. 15. Curves of noise figure versus pump power

Fig. 16. Curves of signal gain (net gain) versus signal power