Extraordinary Figure-of-Merit of Magnetic Resonance from Ultrathin Silicon Nanohole Membrane as All-Dielectric Metamaterial

Metamaterial allows novel nanophotonic applications such as negative permeability, negative refractive index, and near-zero index. In particular, all-dielectric metamaterials recently create new opportunities for manipulating electromagnetic fields, taking full advantage of low-loss, bandwidth enhancement, and isotropic responses. Here a silicon dielectric metamaterial is reported in near-infrared region, exhibiting extraordinarily figure-of-merit, defined by sensitivity (resonance shift/refractive index change) over full width at half maximum, from magnetic resonance shift depending on index changes of surrounding medium. This silicon dielectric metamaterial comprises subwavelength nanohole arrays in a square lattice on an ultrathin amorphous silicon membrane. The ultrathin silicon nanohole membrane is fabricated on a glass wafer by using e-beam lithography, silicon reactive ion etching, and hydrogen fluoride wet etching. This all-dielectric metamaterial successfully demonstrates exceptional figure-of-merit of 29, which is 7.6 times higher than those values of conventional metamaterials. This novel metamaterial enables not only the label-free detection of chemical and biological molecules with different mass concentrations but also the in situ reaction monitoring of biochemical molecules.