Mid-infrared supercontinuum generation in single mode fluoride fiber

We numerically investigate mid-infrared supercontinuum generation in single mode fluoride fiber pumped by 1.56 mu m femtosecond fiber lasers. To get high energy conversion efficiency in mid-infrared region, the ratio of power generated in 2.5 similar to 5 mu m range to the total input power for supercontinuum generation is optimized by varying the pulse width, peak power and fiber length. The long wavelength edge of the supercontinuum spectrum can be extended to 5 mu m in a 9 cm long fluoride fiber pumped by a 1.56 mu m fiber laser with a pulse width of 200 fs and a peak power of 2 MW, and the corresponding ratio of power generated in 2.5 similar to 5 mu m range to the total input power is about 29.6%. The spectral broadening is mainly caused by self-phase modulation, stimulated Raman scattering and four-wave mixing. The simulated results show that high energy conversion power supercontinuum light source in 2.5 similar to 5 mu m range could be obtained in fluoride fibers pumped by 1.56 mu m femtosecond fiber lasers.