Nonlinear optical responses in two-dimensional transition metal dichalcogenide multilayer: WS2, WSe2, MoS2 and Mo 0.5 W0.5 S2

S Bikorimana; P Lama; A Walser; R Dorsinville; S Anghel; A Mitioglu; A Micu; L Kulyuk

doi:10.1364/OE.24.020685

Nonlinear optical responses in two-dimensional transition metal dichalcogenide multilayer: WS₂, WSe₂, MoS₂ and Mo _0.5 W_0.5 S₂

Opt Express. 2016 Sep 5;24(18):20685-95. doi: 10.1364/OE.24.020685.

Authors

S Bikorimana, P Lama, A Walser, R Dorsinville, S Anghel, A Mitioglu, A Micu, L Kulyuk

PMID: 27607672
DOI: 10.1364/OE.24.020685

Abstract

Synthetic two-dimensional transition metal dichalcogenides such as, tungsten disulphide (WS₂), tungsten diselenide (WSe₂), molybdenum disulphide (MoS₂) as well as mixed molybdenum tungsten disulphide (Mo_0.5W_0.5S₂) single crystals were grown by the chemical vapor transport method using halogens (bromine or chlorine) as transport agents. Multi- layer samples were cleaved from the single crystals, and their nonlinear optical (NLO) properties were obtained from both open aperture and closed aperture Z-scan measurements using a picosecond mode-locked Nd: YAG laser operating at a wavelength of 1064 nm, with pulse duration of 25 ps, and 20 Hz repetition rate. Both WS₂ and MoS₂ exhibited nonlinear saturable absorption (SA), whereas WSe₂ and Mo_0.5W_0.5S₂ showed nonlinear two-photon absorption (2PA). A large 2PA coefficient β as high as + 1.91x10^-8 cm/W was obtained for the Mo_0.5W_0.5S₂, and an index of refraction coefficient γ = -2.47x10^-9 cm²/W was obtained for the WSe₂ sample.