Wavelength switchable mode-locked fiber laser with a few-mode fiber filter

We have proposed and constructed a few-mode fiber (FMF)-based comb filter realized by dislocation splicing a few-mode long-period fiber grating (FM-LPFG) with a single-mode fiber (SMF). From an all-fiber laser with a FMF-based comb filter, the generation of switchable single-, dual-, triple-, and quadruple-wavelength continuous light has been achieved. Moreover, wavelength switchable mode-locked pulses have been obtained with the increased pump power. In the experiment, the output wavelength of the mode-locked fiber laser was changed from 1567.72 nm to 1571.04 nm, while the signal-to-noise (SNR) ratio was maintained above 61 dB. The switchable multiwavelength continuous wave (CW) and mode-locked all-fiber lasers have potentially important applications for fiber sensing, wavelength-division multiplexing (WDM) and signal processing.