Third order nonlinear optical property of WSe2 nanofilm at 800 nm

Abstract A tungsten selenide (WSe2) nanofilm was successfully prepared by liquid phase exfoliation. Open and closed aperture Z-scan techniques were used to distinguish between the real and imaginary parts of the third-order optical nonlinearity of the WSe2 nanofilm at 800 nm. The WSe2 nanofilm exhibits excellent saturable absorption characteristics at this waveband. A saturation light intensity of 147 ± 9 GW/cm2, a modulation depth of 24% and a nonlinear refractive index coefficient of about −1.36 × 10−10 cm2/W were obtained. The results reveal that the WSe2 nanofilm is an excellent third order nonlinear optical material, and has potential applications ranging from ultrashort pulse laser mode-locking to optical Kerr-based photonic devices in the 800 nm wavelength range.