Electromagnetic simulation of paired-wire and u-shaped resonator metamaterial composites for terahertz and optical frequencies

In a previous work, the present authors have demonstrated that the requisite electric-type response in a double-negative material can be realized by properly orientating single SRRs, whose particle size is small compared to the wavelength. Since it is necessary to orient these electric SRRs so that they are orthogonal to the k-vector of the incident wave, it is possible to deposit them on the same substrate that is used to print the paired wires. For operation in the mid-infrared frequency range, the SRRs should be replaced by U- shaped (horse-shoe) resonators, and a unit cell of infrared metamaterial can be realized by combining paired wires with U-shaped resonators that also exhibit bianisotropy in common with the SRRs. In this paper we use the finite difference time domain (FDTD) method to investigate the frequency response of a composite wire-pair and U- shaped resonators, forming a unit cell, to see if they produce the desired metamaterial characteristics we seek.