Enhancement of light extraction based on nanowire hyperbolic metamaterials in a grating structure

Abstract

Hyperbolic metamaterial (HMM) has attracted considerable attention owing to several exotic optical properties, including negative refraction, enhanced spontaneous emission, and subwavelength imaging. The hyperbolic dispersion of HMMs increases photonic density of states in a broad bandwidth, leading to enhancement of spontaneous emission. However, the out-coupling of light from HMMs is difficult due to the evanescent character of the high-k modes at the surface. In this study, we implement the full-field numerical calculations based on finite-difference time-domain (FDTD) method to characterize the optical properties of nanowire HMMs embedded in a grating structure. We first examined the power spectrum of the nanowire HMMs. The Purcell factor and the light enhancement are also analyzed. Furthermore, to examine the out-coupling of light by virtue of the periodic structure, the Purcell factor and enhancement of light extraction efficiency of the hybrid structure will be examined and discussed. The analysis result is important toward engineering highly-efficient photonic devices based on HMMs.