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

• Published in: Optical materials 2019-10, Vol.96, p.109271, Article 109271
• Main Authors: Neupane, Tikaram, Yu, Sheng, Rice, Quinton, Tabibi, Bagher, Seo, Felix Jaetae
• Format: Article
• Language: English
• Subjects: Atomic layer; Third-order optical nonlinearity; WS2; Z-Scan
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2019.109271

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. •The third-order optical nonlinearity of WS2 atomic layer was characterized with open and closed Z-scan techniques.•The magnitude and polarity of optical nonlinearity were depended on the optical excitation and frequency.•The electronic band structures for 1-4 layers were calculated by first principle calculations.•The resonant and non-resonant third-order optical nonlinearities of WS2 were depended on the excitation energy.•The third-order optical nonlinearity of WS2 atomic layers were characterized with Z-scan and I-Scan techniques.•The open and closed Z-scan of WS2 atomic layers displayed positive nonlinear absorption and negative nonlinear refraction.•The nonlinear absorption and refraction coefficients of WS2 were estimated to be ~ 6.0 x10-8 m/W and ~-3.8 x 10-15 m2/W.