Modeling S and C-band optical amplification in thulium and erbium codoped fluoride fiber

Theoretical model for Er3+, Tm3+ codoped fluoride fiber based on the rate and propagation equations has been established by considering the energy transfer process between Er3+ and Tm3+, Er3+ absorption in S-band as well as Tm3+ absorption in C-band. The spectral gain as functions of the Er3+ concentration, the fiber length, the pump power has been investigated. Two pumping schemes have been considered and compared with respect to their spectral gains. In the case of Er3+ and Tm3+ codoped fluoride fiber pumped by 0.15 W at 800 nm and 0.3 W at 1410 nm, a gain of 20 dB or more can be achieved in the range of 1450-1560 nm. The results show that significant S + C-band gain can be achieved by codoping Er3+ in Tm3+ doped fluoride fiber and using the dual-wavelength pumping scheme.