利用光谱滤波器实现自启动的全光纤超短脉冲掺Yb^(3+)光纤激光器

All-fiber ultrashort Yb^(3+) doped fiber laser self-started by spectral filter

讨论了利用光谱滤波器实现自启动的被动锁模掺Yb3+光纤环形激光器的锁模机理,并研制出全光纤结构超短脉冲掺Yb3+光纤环形激光器.使用980nm二极管激光器作为抽运源,高掺杂浓度掺Yb3+光纤作为增益介质.在净群速度色散为正的环形腔中加入光谱滤波器,抑制Yb3+离子在1030nm强发射峰的同时,通过对啁啾脉冲的光谱滤波实现脉冲压缩.光谱滤波器与光纤非线性偏振旋转效应相结合,实现了激光器在1053nm可自启动、十分稳定的锁模运转.激光器锁模阈值功率300mW,平均斜率效率18.3%,最大输出功率53.07mW,对应最大输出脉冲能量3.2nJ.锁模光脉冲中心波长1053.6nm,3dB带宽10.84nm,重复频率16.45MHz.锁模脉冲宽度为皮秒量级,经腔外光栅对压缩至188fs.

Theory of the passively mode-locked Yb3 ＋ doped fiber ring laser self-starting through spectral filter is presented. The all-fiber Yb3 ＋ doped fiber ring laser generating ultrashort pulses are designed and fabricated. High concentration Yb3 ＋ doped fiber was employed as gain medium,which was pumped by a 980 nm diode laser. In the all-normal-dispersion cavity,a spectral filter was spliced to reduce the large emission peak at 1030 nm of Yb3 ＋ ion and to generate an additional pulse shaping through spectral filtering of chirped pulse. Self-starting and stable mode-locking centered at 1053 nm was achieved by nonlinear polarization evolution along with spectral filtering from the filter. The mode-locking threshold was 300 mW,with the slope efficiency of 18. 3% ,the maximum output power was 53. 07 mW,corresponding to the maximum pulse energy of 3. 2 nJ. The center wavelength of the mode-locked pulse was 1053. 6 nm,with 3 dB bandwidth of 10. 84 nm at the repetition rate of 16. 45 MHz. The picosecond mode-locked pulse can be dechirped to 188 fs using grating pair outside the cavity.