耗散孤子和束缚态脉冲可切换的超连续谱产生

当超短脉冲进入高非线性光纤时，在色散和非线性效应的共同作用下，脉冲频谱中会产生一些新的频率分量，使得输出频谱比输入频谱宽得多。这种光谱被称为超连续谱。超连续谱光源具有光谱范围宽、方向性好、亮度高、空间相干性好等优点。在锁模激光器中，传统孤子、耗散孤子和类噪声脉冲可以作为种子源产生超连续谱。文中，笔者建立了一个NPR被动锁模光纤激光器来产生脉冲激光。然后，添加一段DCF以补偿腔中的色散，从而产生耗散孤子。同时，通过调节腔内PC，可以实现束缚态和耗散孤子的状态切换。输出脉冲经10 m单模光纤压缩后注入部分拉锥后的高非线性光纤以产生超连续谱。实验中，我们得到了脉宽为5.6 ps、重复频率为32 MHz、信噪比为52 dB的耗散孤子锁模脉冲，压缩后的脉冲宽度为868 fs，用作超连续谱产生。超连续谱的覆盖范围约为1200~2200 nm，其20 dB谱宽为357 nm。通过调节偏振控制器，实现耗散孤子脉冲与束缚态脉冲之间的切换，束缚态脉冲持续时间为1.4 ps，脉冲间隔为14 ps，信噪比为51 dB，产生1600~1870 nm的超连续光谱，20 dB的光谱宽度为135 nm。

Supercontinuum generation assisted by dissipative and bound state pulse switchable

When an ultrashort pulse bursts into a highly nonlinear fiber, some new frequency components are generated in the pulse spectrum under the combined action of dispersion and nonlinear effects, which makes the output spectrum much broader than the input spectrum. The spectrum is called the supercontinuum. Supercontinuum light sources have the advantages of a wide spectral range, good directivity, high brightness, and good spatial coherence. In mode-locked lasers, traditional solitons, dissipative solitons, and noise-like pulses can be used as seed sources to generate a supercontinuum spectrum. In this paper, we build an NPR passively mode-locked fiber laser to generate pulsed laser. Then, a section of DCF is added to compensate for the dispersion in the cavity to produce dissipative solitons. Meanwhile, the states of bound states and dissipative solitons can be switched by carefully adjusting the paddles of PC in the cavity. The output pulse is compressed by a 10 m single-mode fiber before being injected into a tapered highly nonlinear fiber to generate a supercontinuum. In the experiment, we obtain a dissipative soliton mode-locked pulse with a pulse duration of 5.6 ps, a repetition frequency of 32 MHz, and a signal-to-noise ratio of 52 dB. The compressed pulse duration is 808 fs, which is used as the seed to generate a supercontinuum. The cover range of the supercontinuum is approximately 1200 nm to 2200 nm, and its 20 dB spectrum width is 357 nm. By tuning the polarization controller, the switch between the dissipative soliton pulse and the bound state pulse is realized. The pulse duration of the bound state is 1.4 ps, the pulse separation is 14 ps, and the signal-to-noise ratio is 51 dB, which produces a supercontinuum spectrum of 1600-1870 nm with a 20 dB spectral width of 135 nm.