ABSTRACT
Rectangular, millimeter-scale complementary split ring resonators were fabricated, employing the so-called Computer Numerical Control method, combined with a home-built mechanical engraver. Their electromagnetic performance was thoroughly investigated with respect to their dimensions in the frequency regime between 2 and 9 GHz via combining experiments and corresponding theoretical simulations, wherein a considerably effective consistency was obtained. Moreover, their sensing response was extensively investigated against various aqueous solutions enriched with typical fertilizers used in agriculture, as well as detergents commonly used in every-day life. Corresponding experimental results evidently establish the capability of the studied metasurfaces as potential sensors against water pollution.
ABSTRACT
Graphene is an attractive two-dimensional material for nonlinear applications in the THz regime, since it possesses high third order nonlinearity and the ability to support tightly confined surface plasmons. Here, we study 2D-patterned graphene-patch metasurfaces for efficient third harmonic generation. The efficiency of the nonlinear process is enhanced by spectrally aligning the fundamental and third harmonic frequencies with resonances of the metasurface, leading to spatiotemporal energy confinement in both steps of excitation at ω and radiation at 3ω. This precise resonance alignment is enabled by the 2D-patterning; it is achieved by modifying the dispersion of the underlying plasmons and, thus, the spectral positions of the supported standing wave resonances. Efficiencies as high as -20dB (1%) for input intensity 0.1 MW/cm2 are achieved. Moreover, we verify that the efficiency does not deteriorate when finite-size metasurfaces are used in place of ideal periodic systems. Our results highlight the potential of graphene-based metasurfaces for nonlinear applications.
