Third-order optical nonlinearity of tungsten disulfide atomic layer with resonant excitation

Abstract The third-order optical nonlinearity of tungsten disulfide atomic layer was characterized with open and closed Z-scan techniques with a resonant excitation near an exciton absorption peak using a pulsed laser which has a temporal pulse width of ~6 ns and a Gaussian spatial beam profile. The normalized transmittance traces with open and closed Z-scan for the WS2 atomic layers displayed positive nonlinear absorption and negative nonlinear refraction. The nonlinear absorption and nonlinear refraction coefficients of WS2 with the resonant excitation were estimated to be ~6.0 × 10−8 m/W and ~-3.8 x 10−15 m2/W.