Spectroscopic characterization of signal gain and pump ESA in short-lengths of RE-doped tellurite fibers

We report the results of emission and amplification in Tm3+- and Er3+-fibers for signal gain in the 1460–1600 nm region, which covers a large part of S-, C- and L-bands of silica fiber optical communication networks. The paper explains the mechanism for alleviating the pump-excited absorption in Er3+-doped and Tm3+-doped tellurite fibers for maximizing the pump inversion efficiency at 980 nm using the co-dopants and via the structural modification of TeO2 glass by incorporating a high phonon energy oxide namely, B2O3. The spectroscopic data and gain bandwidth of Er-doped fibers are reported in the C- and L-bands. To date the measured maximum relative gain in short fibers of 5–10 cm in length in C- and L-bands are: 30 dB and 15 dB, respectively. By comparison the internal gain in a 20 cm long Tm/Yb ion co-doped fiber pumped with a 980 nm source was 7 dB.