位于第三近红外窗口的平坦光纤超连续谱产生

报道了一种基于非线性偏振旋转效应的被动锁模光纤激光器。采用980 nm分布式反馈激光器作为泵浦源，0.5 m长的高掺杂掺铒光纤作为增益介质。实现了脉冲宽度为822 fs的传统孤子锁模脉冲，输出脉冲的平均功率为2.8 mW，信噪比为55.8 dB。通过微调腔内的偏振控制器，实现了传统孤子脉冲和孤子分子脉冲间的切换，孤子分子的脉冲宽度为312 fs，信噪比为53.86 dB。孤子分子脉冲经掺铒光纤放大器放大后泵浦一段57 m长的高非线性光纤，产生了位于第三近红外窗口（1600 nm～1870 nm）的超连续谱，其20 dB谱宽为355.8 nm。

Flat fiber super-continuum spectrum generation in the third near-infrared window

A passively mode-locked fiber laser based on nonlinear polarization rotation mechanism was reported. The 980 nm distributed feedback laser was used as the pump source and the highly doped erbium-doped fiber with length of 0.5 m was used as the gain medium. The traditional soliton mode-locked pulse with the pulse width of 822 fs was realized, the average power of the output pulse was 2.8 mW, and the signal-to-noise ratio (SNR) was 55.8 dB. By adjusting the polarization controller slightly in the cavity, the switch between traditional soliton pulse and soliton molecule pulse was realized, the pulse width and the SNR of the soliton molecule were 312 fs and 53.86 dB, respectively. The soliton molecule pulse was amplified by the erbium-doped fiber amplifier to pump a 57 m long high nonlinear fiber, which produced a super-continuum spectrum located in the third near-infrared window (1 600 nm~1 870 nm) with a 20 dB spectrum width of 355.8 nm.