Exact solutions of Maxwell's equations describing the lightwave through 3-layer-structured cylindrical waveguide are obtained and the mode field diameter and nonlinear coefficient of air-core nanowires (ACNWs) are numerically calculated.The simulation results show that ACNWs offer some unique optical properties,such as tight field confining ability and extremely high nonlinearity.At a certain wavelength and air core radius,we optimize the waveguide design to maximize the nonlinear coefficient and minimize the mode field diameter.Our results show that the ACNWs may be powerful potential tools for novel micro-photonic devices in the near future.
