Coupling effects in low-symmetry planar split-ring resonator arrays

We introduce a particular low-symmetry (point group of unit cell C(1)) planar periodic arrangement of magnetic split-ring resonators that acts as an effective optical wave plate. We show that this behavior specifically results from the in-plane interactions among the individual split-ring resonators. Measured normal-incidence transmittance and conversion spectra of gold-based samples fabricated via electron-beam lithography show fundamental resonances at around 235 THz frequency (1,275 nm wavelength) that are in good agreement with theory.