Bidirectional fiber soliton laser mode-locked by single-wall carbon nanotubes

We report on the experimental observation of a bidirectional fiber soliton laser passively mode-locked by single-wall carbon nanotubes. Two stable pulse trains in opposite directions are delivered simultaneously from the ring cavity. The counterpropagating pulses have different central wavelengths, pulse durations, and repetition rates. By adjusting the fiber birefringence and cavity length, the central wavelengths of two solitons can be the same or different. Experimental observations and analyses demonstrate that the different operating wavelengths result in the unequal repetition rates of two pulses. These unique features may be attributed to the cavity asymmetry and fiber birefringence.