Tunable nonlinear refractive index of two-dimensional MoS2, WS2, and MoSe2 nanosheet dispersions [Invited]

Liquid-phase-exfoliation technology was utilized to prepare layered MoS2, WS2, and MoSe2 nanosheets in cyclohexylpyrrolidone. The nonlinear optical response of these nanosheets in dispersions was investigated by observing spatial self-phase modulation (SSPM) using a 488 nm continuous wave laser beam. The diffraction ring patterns of SSPM were found to be distorted along the vertical direction right after the laser traversing the nano-sheet dispersions. The nonlinear refractive index of the three transition metal dichalcogenides dispersions n(2) was measured to be similar to 10(-7) cm(2) W-1, and the third-order nonlinear susceptibility. chi((3)) similar to 10(-9) esu. The relative change of effective nonlinear refractive index Delta(n2e/n2e) of the MoS2, WS2, and MoSe2 dispersions can be modulated 0.012-0.240, 0.029-0.154, and 0.091-0.304, respectively, by changing the incident intensities. Our experimental results imply novel potential application of two-dimensional transition metal dichalcogenides in nonlinear phase modulation devices. (C) 2015 Chinese Laser Press