Nonlinear optical performance and mechanism in MoS₂/WS₂ van der Waals heterostructures

Two-dimensional transition metal dichalcogenides have been widely used due to their excellent nonlinear optical properties. To enhance the optical nonlinearity of transition metal dichalcogenides, some van der Waals heterostructures have been designed, and the carrier dynamics play a key role in the nonlinear response. In this paper, the optical nonlinearity of molybdenum disulfide/tungsten disulfide heterostructures was investigated by nanosecond laser Z-scan technology, and enhanced saturable absorption behavior was found in heterostructures. Using femtosecond time-resolved transient absorption measurements, the carrier dynamics in the nonlinear response, as well as the enhancement mechanism of the heterostructures, were further clarified.