Gain improvement by internal laser cavity in Tm(3+)Yb(3+)-co-doped tellurite fiber amplifier pumped by 980-nm laser.

S-band Tm(3+)/Yb(3+) co-doped tellurite fiber amplifier pumped by a 980 nm laser diode is proposed and modeled taking into consideration of the energy transfer process from Yb(3+) to Tm(3+) and the laser cavity inside a co-doped fiber amplifier. S-band spectral gains for the co-doped fiber amplifiers are investigated. The results show that considerable gain improvement can be achieved by constructing 1050nm laser cavity inside the amplifier.