An advanced method based on FDTD to extract the indices of composite meta-material

An advanced method was introduced to determine the negative indices of the composite meta-material. The macroscopic configuration of meta-material simulated in FDTD was a slab of finite thickness. A genuine plane wave normally incident on the slab was simulated by FDTD and the phase of the total field was extracted with an optimized phase extraction technique. The phase of the total field was verified to vary monotonously along the center of the slab. According to this property, the wavelength, the phase velocity and refraction index of the electromagnetic wave in the meta-material were readily determined. As comparison to our method, the conventional method to determine refraction index with Snell's law was also performed. The results of our method and the conventional method are in good agreement. But our novel method cut down the computational domain more than 30 times and greatly save the computation time.