Switchable femtosecond and picosecond spatiotemporal mode-locked fiber laser based on NALM and multimode interference filtering effects

•An all-few-mode fiber spatiotemporal mode-locked figure-8 laser at 1.55 µm is constructed.•The switchable generation of femtosecond and picosecond spatiotemporal mode-locked pulses is achieved for the first time.•Both in the femtosecond and picosecond pulse regimes, the pulse-pattern-tunable operation can be achieved.•The switching principle between the femtosecond and picosecond pulses is theoretically analyzed.