Erbium-doped fiber laser passively mode locked with few-layer WSe 2 /MoSe 2 nanosheets

Few-layer transition-metal dichalcogenide WSe 2 /MoSe 2 nanosheets are fabricated by a liquid exfoliation technique using sodium deoxycholate bile salt as surfactant, and their nonlinear optical properties are investigated based on a balanced twin-detector measurement scheme. It is demonstrated that both types of nanosheets exhibit nonlinear saturable absorption properties at the wavelength of 1.55 μm. By depositing the nanosheets on side polished fiber (SPF) or mixing the nanosheets with polyvinyl alcohol (PVA) solution, SPF-WSe 2 saturable absorber (SA), SPF-MoSe 2 SA, PVA-WSe 2 SA, and PVA-MoSe 2 SA are successfully fabricated and further tested in erbium-doped fiber lasers. The SPF-based SA is capable of operating at the high pump regime without damage, and a train of 3252.65 MHz harmonically mode-locked pulses are obtained based on the SPF-WSe 2 SA. Soliton mode locking operations are also achieved in the fiber laser separately with other three types of SAs, confirming that the WSe 2 and MoSe 2 nanosheets could act as cost-effective high-power SAs for ultrafast optics.