Switchable linear-cavity nanotube-mode-locking fiber laser emitting picosecond or femtosecond pulses

A switchable linear-cavity nanotube-mode-locking fiber laser is proposed by exploiting fiber Bragg grating for the first time to the author׳s best knowledge. The proposed all-fiber laser can deliver either picosecond or femtosecond pulses by controlling the polarization controllers. The durations of picosecond and femtosecond pulses are 16.4 ps and 838 fs with the central wavelengths of 1529.5 and 1560 nm, respectively. The femtosecond pulse has symmetrical spectrum sidebands, but the picosecond pulse almost has no spectral sidebands. Our work provides a simple, low-cost, dual-scale pulse source for practical applications.