Mid-infrared designer metals.

We demonstrate the potential of highly-doped semiconductor epilayers as building blocks for mid-infrared plasmonic structures. InAs epilayers are grown by molecular beam epitaxy and characterized by Hall measurements and optical techniques. We show that the plasma frequency of our material can be controlled across a broad range of mid-infrared frequencies. Subwavelength disks are fabricated out of our material, and localized plasmonic resonances are observed from these structures. Experimental results are compared to both numerical simulations and a simple quasistatic dipole model of our disks with good agreement.