Broadband ultrafast nonlinear optical response of few-layers graphene: toward the mid-infrared regime

Abstract

Gapless linear energy dispersion of graphene endows it with unique nonlinear optical properties, including broadband nonlinear absorption and giant nonlinear refractive index. Herein, we experimentally observed that few-layers graphene has obvious nonlinear absorption and large nonlinear refraction, as investigated by the Z-scan technique in the mid-infrared (mid-IR) regime. Our study may not only, for the first time to our knowledge, verify the giant nonlinear refractive index of graphene (similar to 10(-7) cm(2)/W) at the mid-IR, which is 7 orders of magnitude larger than other conventional bulk materials, but also provide some new insights for graphene-based mid-IR photonics, potentially leading to the emergence of several new conceptual mid-IR optoelectronics devices. (C) 2015 Chinese Laser Press