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.