Recently, ultrafast optical modulators (OMs) based on atomic transition-metal dichalcogenides (TMDs) film have been intensively explored. Benefited from their remarkable nonlinear saturable absorption properties, TMDs based OMs could be employed as critical devices for pulsed lasers systems to transit continuous wave into pulse trains in laser cavity. Herein, the few-layer TMDs films were grown by chemical vapor deposition (CVD) method in possession of uniform thickness, large areas and high crystal quality. Then two types TMDs based OMs were fabricated by integrating single TMDs film or van der waals heterostructures (VdWHs) on the target substrates. As for VdWHs based OMs, different few-layer TMDs films were vertically stacked in turns on the target substrates to form heterointerfaces, which has been demonstrated with ultrafast carrier relaxation time between neighbor layers recently and is favor for ultrafast pulse generation. In our experiments, the nonlinear optical properties of two types TMDs based OMs were systematically investigated by measuring their nonlinear saturable absorption curves and further compared by embedded them into same fiber laser systems. The results indicate that the VdWHs based OMs owns more excellent nonlinear optical properties (such as larger modulation depth, smaller saturable intensity) and offers a feasible strategy to engineer desired ultrafast photonics devices by modifying the structure of VdWHs.
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