Nonlinear multimodal interference as ultrafast photonic device for dual-wavelength DW dark pulse generation

Abstract

In comparison to bright pulses, better stability and not susceptible to losses, making dark pulses accessible for applications in such fields as signal processing, optics sensing and quantum communication. Here we investigate the dual-wavelength domain-wall (DW) dark pulse generation in a graded-index multimode fiber (GIMF) based anomalous dispersion single-mode fiber (SMF) laser for the first time, to the best of our knowledge. By optimizing intra-cavity nonlinearity and pulse polarization, the mode-locked states can evolve each other between bright pulses, dark pulses and bright-dark pulse pairs. The evolution mechanism among them may be relevant to the coherent mode superposition, spectral filtering, and mode selection in SMF-GIMF-SMF hybrid-fiber modulation device that affect the pulse formation and evolution in the temporal, frequency, and space domains respectively. These results provide a valuable reference for promoting the further development of the nonlinear optics and ultrafast optics, in which ultrafast photonic device, with low cost, simple manufacture as well as wide adaptability, as novel pulsed generation technique, plays vital role.