Comparison between the single and dual-pumping method of large mode area Yb3+/Tm3+ co-doped air-clad fiber laser

The large mode area Yb³⁺/Tm³⁺ co-doped air-clad photonic crystal fiber laser (YTD-PCF) is demonstrated using a fiber Bragg grating (FBG) in a linear cavity resonator. The effect on the performance of the lasing efficiency between the two different doping concentrations of the Yb³⁺/Tm³⁺ ions is investigated. The newly developed fiber used in this experiment has Yb³⁺/Tm³⁺ ion concentration ratio of 4:1 and 2.5:1. The threshold is obtained at 1000 mW with a slope efficiency of 0.96% for higher Yb³⁺/Tm³⁺ ion concentration. Result shows that higher Yb³⁺ ion concentration gives better performance in terms of lasing´s threshold and efficiency. The different types of pumping scheme which is single and dual-pumped have been compared. In the dual-pumping scheme, pump wavelength of 927 nm and 905 nm are used as a main and an auxiliary pump alternately. The high efficiency is attributed to the use of additional 927 nm pump to complement 905 nm pumping. The maximum output power of 11.7 mW is achieved at the pump power of 2500 mW with the optimum length of 2 m.