Broadband third order nonlinear optical responses of bismuth telluride nanosheets

We experimentally observed that a representative two-dimensional layered material, bismuth telluride (Bi2Te3) nanosheets, exhibit obvious broadband nonlinear absorption and large nonlinear refraction investigated by Z-scan technique. Our study may not only verify the giant nonlinear refractive index of Bi2Te3 (~10−8 cm2/W), but also provide some new insights for topological insulator-based photonics, potentially leading to the emergence of several new conceptual optoelectronics devices.