Rare-earth oxide doped single and multi-cores heavy metal oxide fibres for lasers and amplifiers

We report recent developments on rare-earth ion doped heavy metal-oxide glass fibres for engineering lasers and amplifiers, operating in the optical communication window. Special emphasis on rare-earth ion co-doping schemes for controlling the pump excited state absorption process, which is dominant in the single mode fibre geometry, is explained by demonstrating enhanced gain, specially in the 1520 to 1610 nm band, using a 22 cm long Er³⁺-Ce³⁺ doped tellurite fibre. Our investigation also demonstrates how a triple core fibre structure with Tm³⁺-Yb³⁺, Er³⁺-Ce³⁺, and Tm³⁺-Ho³⁺-Yb³⁺ co-doping can be excited with a high-power 980 nm source through cladding pump scheme to generate ASE in the 1500-2050 nm region.