Watt-level 815 nm lasing from Tm³⁺-doped fluorotellurite glass fibers

Tm³⁺-doped fluorotellurite fibers based on TeO₂-BaF₂-Y₂O₃(TBY) glasses were fabricated by using a rod-in-tube method. By using an 81 cm-long Tm³⁺-doped fluorotellurite fiber as the gain medium and a 1400 / 1570 nm dual-wavelength pump technique, lasing at 815 nm was obtained for a threshold pump power of 629 mW at 1400 nm and a fixed pump power of 960 mW at 1570 nm. As the 1400 nm pump power is increased to 1803 mW, the obtained maximum output power was about 1616 mW. The corresponding optical-to-optical conversion efficiency was about 58.5%. Our results show that Tm³⁺-doped fluorotellurite fibers are promising gain media for constructing 815 nm fiber lasers.