Dual-wavelength passively Q-switched Erbium doped fiber laser based on an SWNT saturable absorber

We report a dual-wavelength, all-fiber, passively Q-switched Erbium doped fiber laser based on a single-wall carbon nanotube saturable absorber. By just varying the pump power to balance the peaks of the Erbium doped fiber gain spectra in the cavity, the laser can operate in the dual-wavelength Q-switching regime without intracavity spectral filters or modulation elements. Our experimental results show that the fiber laser can simultaneously generate Q-switched microsecond pulses at ∼1532 nm and ∼1558 nm, which have the same repetition rate of tens of kHz and around 0.5 nJ pulse energies. Our scheme is quite simple to implement at a low cost.