All-fiber wavelength-tunable mode-locked cylindrical vector beams laser based on multimode interference

•The NL-MMI-based single- and dual-wavelength tunable mode-locked CVBs fiber laser is demonstrated, to the best of our knowledge, for the first time.•The single wavelength tuning range of 1541–1564 nm with a maximum spacing of 23 nm.•The dual-wavelength tuning ranges from 1542.8 and 1562.925 nm to 1546.52 and 1563.86 nm, with a maximum spacing of 20.125 nm.•The single-wavelength mode-locking state can be easily switched to the dual-wavelength mode-locking state by adjusting the PC state without the need for additional adjustment devices.•The purity of CVBs was assessed to be 94.4%, providing new insights into the information-carrying capacity of the broadened communication link. Cylindrical vector beams (CVBs) are of increasing concern due to their polarization and axially symmetrical distribution of field intensity. In this paper, we report for the first time an all-fiber single- and dual-wavelength tunable CVBs fiber laser using the nonlinear optical saturation absorption characteristics and filtering properties of nonlinear multimode interference (NL-MMI). In the experiment, the central wavelength of mode-locked CVBs fiber laser can be tuned from 1541 nm to 1564 nm at single-wavelength and from 1542.8 and 1562.925 nm to 1546.52 and 1563.86 nm at dual-wavelength. This NL-MMI-based wavelength-tunable ultrashort pulse CVBs fiber laser has excellent development prospects in optical communication.