利用锁模光纤激光器在色散位移光纤中产生超连续谱的研究

采用主动锁模光纤激光器输出的重复频率10GHz、脉宽7．97ps的脉冲作为抽运光源，无需压缩后直接抽运4．2km的普通色散位移光纤(DSF)．利用色散位移光纤中自相位调制、交叉相位调制等非线性效应的联合作用，获得了20dB带宽达125nm、覆盖整个C波段、L波段和部分S波段的超连续(SC)谱。实验研究了抽运光脉冲峰值功率和抽运波长对超连续谱宽度的影响，结果表明抽运光脉冲峰值功率越高，得到的超连续谱的带宽越宽；通过对抽运波长的优化，可以实现最大程度的超连续展宽；分析了滤波器带宽对脉冲质量的影响；利用0．4nm带宽的可调谐滤波器对从超连续谱中滤出脉冲的特性进行了研究，在超连续谱的不同波长处获得了脉宽为8．90～9．80ps、时间一带宽积为0．44～0．49的稳定的窄光脉冲。

Studies on Supercontinuum Generation in Dispersion Shifted Fiber by Using Mode-Locked Fiber Laser

The 20 dB-bandwidth of 125 nm covering the whole C, L bands and part of S band of supercontinuum (SC) in a 4.2 km dispersion-shifted fiber (DSF) was obtained in the experiment, which was based on the actively mode-locked erbium-doped fiber laser (AMLFL) with the repetition rate of 10 GHz and the pulse duration of 7.97 ps. The dispersion-shifted fiber (DSF) was pumped by the output pulses from the AMLFL without being compressed. In a DSF, the supercontinuum results from combined interaction of nonlinear effects including self-phase modulation (SPM) and cross-phase modulation (XPM). The influences of peak powers and wavelengths of pumping pulse on supercontinuum (SC) spectrum were experimentally investigated. It is clear that the generated supercontinuum could be broadened further when the pump pulse peak power is increased; The broader supercontinuum could be got by optimization of pump wavelength; At the same time, the characteristics of pulses which are filtered out from supercontinuum spectrum by tunable filter with 0.4 nm bandwidth were studied. The stable, narrow optical pulses with pulse-width of 8.90～9.80 ps and time-bandwidth product of 0.44～0.49 were filtered out from the supercontinuum at different wavelengths.