Dark Pulse Laser With Tunable Width Based on SOA and Feedback

We demonstrate a dark pulse optical fiber laser with tunable widths based on semiconductor optical amplifier and feedback. In the case of different feedback lengths, by adjusting the polarization controller, dark pulses with a frequency repetition of 13.3 MHz and widths vary from 4.29 to 15.15 ns are generated. Dark pulses are produced by the interaction of birefringence, large normal dispersion, cross-phase modulation, and cross-gain modulation in semiconductor optical amplifier.