Nowadays, the multimode fiber (MMF), which was overlooked for decades, is making a strong comeback since it can address plenty of long-standing issues relating to the single-mode fiber (SMF). For optical communication, based on the spatial division multiplexing technique[1,2], MMF can enhance the transmission capacity through adding the mode degree of freedom. In addition, MMF can meet the ever-increasing demands for high power laser through increasing the mode area to reduce the nonlinear effects. Apart from the afore-mentioned applications, MMF also can be applied in imaging[4,5], metrology, quantum processing, and spectroscopy, to name a few. Meanwhile, MMF is also an ideal platform to investigate the complex nonlinear phenomena due to interaction between the transverse modes, such as ultrabroadband dispersive waves generation[9,10], geometric parametric instability[11–13], supercontinuum generation[14–16], spatiotemporal light beam compression, and beam self-cleaning[18–22].