Generation and evolution of bright-dark solitons in Er-doped fiber laser based on ZrTe2 as saturable absorber

We investigate the generation of bright-dark solitons in erbium-doped mode-locked fiber lasers based on ZrTe2 as saturable absorber. By adjusting the pump power and polarization state appropriately, three dual-wavelength mode-locked operations, namely bright soliton, bright-dark soliton pairs, and dark soliton are acquired. At pump power of 230 mW, bright solitons with central wavelengths of 1567.3 and 1568.1 nm, corresponding to 3-dB bandwidths of 0.15 and 0.2 nm, are obtained. For the bright-dark soliton pairs operation, the maximum average output power and largest single-pulse energy are 7.2 mW and 0.69 nJ, respectively. In addition, stable dark solitons with pump power of 300 mW at the fundamental rate of 10.47 MHz are achieved. Our research results indicate that ZrTe2 can operate as excellent saturable absorber for bright-dark soliton generation and will promote the development of ultrafast optics.