Terahertz response and mode coupling in a fractal meta-atom

We investigate the terahertz (THZ) responses of fractal concentric rectangular square resonators (CRS) induced by different mode coupling mechanisms. Near-field coupling results in the resonant mode redshift, while conductive coupling cause the results in the resonant mode blueshift. One can achieve a high Q mode with strong modulation depth by switching the capacitive coupling to conductive coupling in a fractal meta-atom.