A Wavelength-Switchable Passively Harmonically Mode-Locked Fiber Laser With Low Pumping Threshold Using Single-Walled Carbon Nanotubes

We propose and demonstrate a wavelength-switchable passively harmonically mode-locked fiber laser with low pumping threshold using single-walled carbon nanotubes. When the pumping power of 980-nm laser diode is 60 mW, passive mode-locking (PML) of a soliton erbium-doped fiber laser at the 23rd harmonic of fundamental cavity frequency is experimentally observed at the central wavelength of 1530 nm. By only adjusting the polarization of laser in the cavity, another PML at the 13th harmonic is successfully achieved at 1554 nm. The supermode suppression of each wavelength is larger than 30 dB. The pulses at 1530 nm are characterized in detail with a repetition rate of 328.44 MHz, a transform-limited pulsewidth of 1.3 ps, and a timing jitter of 142.6 fs.