Superior Third-order Nonlinearity in Inorganic Fullerene-like WS2 Nanoparticles

Tianlun Li,^1,# Rui Hao,^1,# Lingling Zhang,¹ Jianyong Mao,¹  Feng Li,¹ Yanpeng Zhang,¹  Jixiang Fang,^1,2 and Lei Zhang^1,*

Abstract: Two-dimensional (2D) transition metal dichalcogenides (TMDs) attain increasing attentions due to their exceptional nonlinear optical efficiencies, which hold promising potentials for on-chip photonics and advanced optoelectronic applications. Planar TMDs have been proven to support orders-higher third-order nonlinear coefficient in comparison with common nonlinear materials. Interestingly, stronger light-matter interaction could be motivated when curved features is introduced to 2D TMDs. Here, a type of inorganic Fullerene-like WS2 nanoparticles are chemically synthesized using hard mesoporous silica. By using spatial self-phase modulation (SSPM) method, the nonlinear refractive index n2 and third-order susceptibility χ(3) are investigated at visible range. It is found that n2 ~ 10^-4 cm² W^-1 and χ(3) ~ 10^-6 esu, three-order higher than the counterparts of planar WS2 structures. Our experimental findings provide a fresh thinking in designing nonlinear optical materials and endow TMDs new potentials in photonic integration applications.