Optical amplification covering the entire S-band in Tm3+/Er3+ co-doped fluorotellurite fibers

We demonstrated optical amplification covering the entire S-band in Tm 3+ /Er 3+ co-doped fluorotellurite fibers by using a 1410 nm fiber laser as the pump source. Tm 3+ /Er 3+ co-doped fluorotellurite fibers were fabricated by using a rod-in-tube method. A 10 dB gain bandwidth of ?87 nm (1455-1542 nm) and a maximum gain of ? 21.7 dB at 1520 nm were achieved from a 3 m long Tm 3+ /Er 3+ co-doped fluorotellurite fiber (the doping concentration of Tm 3+ and Er 3+ : 4000 and 750 ppm) for a pump power of ? 1.7 W and an input signal power of ? 0 dBm (1 mW). In comparison with that in Tm 3+ -doped fluorotellurite fibers without Er 3+ doping, the 10 dB gain bandwidth for the above Tm 3+ /Er 3+ co-doped fluorotellurite fiber was improved from 67 nm (1455-1522 nm) to 87 nm (1455-1542 nm, covering the entire S-band), which was due to optical amplification in the long wavelength region of S-band originated from the transition 4 I 13/2 ? 4 I 15/2 of Er 3+ ions combining with that in S-band from the transition of 3 H 4 ? 3 F 4 of Tm 3+ ions. Our results show that Tm 3+ /Er 3+ co-doped fluorotellurite fibers are promising gain media for constructing broadband S-band fiber amplifiers.