Generation of dark-bright pulse pairs using a saturable absorber based on tapered erbium-doped fiber

The dark-bright pulse pairs were obtained in an erbium-doped fiber laser (EDFL) using a saturable absorber based on tapered erbium-doped fiber (T-EDF). The spectrum had two peaks, which located at 1565.5nm and 1566.4nm respectively. The signal-to-noise ratio (SNR) was about 65dB, indicating a relatively stable operation. The dark-bright pulse pairs could be converted into bright-dark-bright pulse pairs through controlling the polarization state within the cavity. The spectral peaks slight shift and the SNR reduced to 43dB. Changing the pump power and polarization states, the bright-dark pulse pairs were obtained. All three types of pulse pairs possess a repetition rate of 10.89MHz. Meanwhile, the orthogonality of the pulse pairs in two polarization directions are experimentally verified via a polarization-resolved system.