2D Ductile Transition Metal Chalcogenides (TMCs): Novel High-Performance Ag2S Nanosheets for Ultrafast Photonics

As a member of 2D transition metal chalcogenides (TMCs), 2D Ag2S with large absorption coefficient, broadband optical response, extraordinary metal-like ductility, high plastic deformation strain, unique layered structure, and very low solubility has offered a platform for achieving disruptive successes in divisional fields. Great achievements have been achieved in exploring the linear optical, mechanical, and photoelectric properties of 2D Ag2S nanosheets. However, the nonlinear optical properties of 2D Ag2S nanosheets and their applications in ultrafast photonics have not been studied. The saturable absorption property of 2D Ag2S nanosheets is experimentally illustrated at the telecommunication band with a large optical modulation depth of 15.5% and a low saturable intensity of 250.4 MW cm(-2). Moreover, 229th harmonic soliton molecule with repetition rate of 1.1 GHz based on 2D Ag2S saturable absorber (SA) is realized at the telecommunication band for the first time to the authors' knowledge. Thankfully, 2D Ag2S nanosheets display excellent nonlinear optical properties suggesting that this may open a new door for advanced photonic devices based on 2D Ag2S nanosheets.