中红外可调谐大能量飞秒脉冲激光产生

Mid-infrared tunable femtosecond fiber laser has attracted many attentions for widely applications. Recently, Raman soliton self-frequency shifting effect in nonlinear fibers was regarded as a promising approach to obtain such pulse laser. However, other higher order nonlinear effects occurred in fibers will limit the pulse energy promoting. So, to further enhance the pulse energy of Raman soliton, we proposed a novel method where the rare-earth doped nonlinear fiber was used as nonlinear medium. We numerically investigated the impacts of the optical gain on the pulse energy, pulse width and spectrum of the wavelength shifting Raman soliton. The results show that as the Raman soliton shifted into the wavelength range where the optical gain introduced, the pulse energy of the soliton pulse was enlarged by several times, and the pulse width was compressed to 45 fs. Meanwhile, the wavelength of the femtosecond Raman soliton pulse can be widely tuned by changing the optical net gain. Therefore, by using rare-earth doped fiber as the nonlinear medium and gain medium, we can achieve the generation of mid-infrared tunable high pulse energy femtosecond pulse laser.