Kerr Nonlinearity in germanium selenide nanoflakes measured by Z-scan and spatial self-phase modulation techniques...

Germanium selenide (GeSe) has attracted considerable research interest due to its unique photoelectric characteristics: high abundance occurrence, low toxicity, high stability, and environmentally sustainable. To the best of our knowledge, less literature is available on the nonlinear optical (NLO) properties of GeSe and on its significance of the electronic structure. In this work, the GeSe nanoflake ethanol suspensions have been studied by using liquid phase exfoliation method and then characterized by Raman, transmission electron microscopy (TEM), transmittance and atomic force microscopy (AFM). The NLO properties of GeSe suspensions with different concentration are investigated by Z-scan and spatial self-phase modulation (SSPM) methods with continuous wave laser, which are coherent with the parameter nonlinear refractive index n2 and the third order nonlinear polarizabilities χ⁽³⁾. The nonlinear refractive index n2 of GeSe dispersions basically occur in the order of 10^-9 cm²/W for Z-scan methods and 10^-6 cm²/W for SSPM technique, whereas the third-order nonlinear polarizabilities χ⁽³⁾ _total are within the range of 10^-6 esu for SSPM method. On the basis of these substantial characteristics of the NLO response and high stability of the 2D GeSe, we have experimentally studied the applications of the GeSe suspensions on all-optical information conversion technique.