Spontaneous Emission in Nonlocal Metamaterials with Spatial Dispersion

Recent successes in fabrication, characterization, numerical computations, and theory have brought to life a new class of composite materials with engineered optical properties, metamaterials. Uniaxial anisotropic artificially created structures based on plasmonic nanowire arrays have emerged as a versatile platform for negative refraction, subwavelength optics, biosensing, acoustic sensing, and nonlinearity engineering. It has been demonstrated, both experimentally and theoretically, that the optical response of plasmonic nanowire arrays is strongly affected by nonlocal electromagnetism, a phenomenon where permittivity of metamaterial strongly depends not only on the frequency, but also on wavevector of the plane wave interacting with this structure. Nonlocal dielectric response leads to excitation of additional electromagnetic wave that does not exist in conventional, local, metamaterials. The dispersion of this wave can be engineered by adjusting composition and geometry of metamaterial. In this chapter we present comprehensive review of nonlocal electromagnetic properties in plasmonic nanowire metamaterials. We begin by introducing the material platform, explain the theoretical approach for nonlocal homogenization, and finally discuss the implication of material nonlocality for emission of light in nonlocal environment.