New propagation regimes for light arise from the ability to tune the dielectric permittivity to extremely low values. Here, we demonstrate a universal approach based on the low linear permittivity values attained in the ε-near-zero (ENZ) regime for enhancing the nonlinear refractive index, which enables remarkable light-induced changes of the material properties. Experiments performed on Al-doped ZnO (AZO) thin films show a sixfold increase of the Kerr nonlinear refractive index (n2) at the ENZ wavelength, located in the 1300 nm region. This in turn leads to ultrafast light-induced refractive index changes of the order of unity, thus representing a new paradigm for nonlinear optics.
- nonlinear optical behaviour
- nonlinear refractive index
- nonlinear optics
Caspani, L., Kaipurath, R. P. M., Clerici, M., Ferrera, M., Roger, T., Kim, J., ... Faccio, D. (2016). Enhanced nonlinear refractive index in epsilon-near-zero materials. Physical Review Letters, 116(23), . https://doi.org/10.1103/PhysRevLett.116.233901