Hyperbolic Metamaterial with Quantum Dots for Enhanced Emission and Collection Efficiencies

Abstract

Bright, room‐temperature stable, on‐demand, and highly directional light sources are essential for quantum optical technologies. A design methodology to enhance the emission and collection efficiencies for given collection optics is proposed and demonstrated. Hyperbolic metamaterials (HMMs) offer manipulation of local density of states to improve the emission as well as coupling of emission to high‐K modes. However, metallic losses limit the efficiencies achieved. The HMM structure designed for large, broadband Purcell enhancement with limited metallic losses as well as HMM and antenna design to optimize the collection efficiency is presented. 200 times emission enhancement is reported from CdSeS/ZnS core/shell alloyed quantum dots embedded in a planar HMM structure with cylindrical silver (Ag) patch antenna on the top. 40% collection efficiency is demonstrated for a lens with a numerical aperture of 0.9 and the emission enhancement is about an order of magnitude higher than the previous reports.

Control of the surface plasmon dispersion and Purcell effect at the metamaterial-dielectric interface

“…Our results are in line with other results reported in works [32][33][34][35][36][37][38] , although the geometry and materials are different. It is hard to determine precisely the value of the Purcell factor in the previous studies 32,33,36 ; however, judging from the decay time decrease, it should be in the range from 10 to 100.…”

“…4c are a consequence of the irregularities in the refractive index values for silver and CBP, to which the peak Purcell factor value is very sensitive. There is almost no difference in peak Purcell factor value for different orientations of the dipole (parallel and www.nature.com/scientificreports/ perpendicular to the interface), contrary to the results reported by Kala et al 35 , where dipole orientation along interface provides negligible Purcell factor values. This discrepancy is, however, the result of different geometries of structures considered in our work and in 35 .…”

“…There is almost no difference in peak Purcell factor value for different orientations of the dipole (parallel and www.nature.com/scientificreports/ perpendicular to the interface), contrary to the results reported by Kala et al 35 , where dipole orientation along interface provides negligible Purcell factor values. This discrepancy is, however, the result of different geometries of structures considered in our work and in 35 . In 35 the structure was symmetrical, and the dipole was placed in its center; as a result, the x-component of the electric field vanishes obliterating Purcell effect.…”

“…This discrepancy is, however, the result of different geometries of structures considered in our work and in 35 . In 35 the structure was symmetrical, and the dipole was placed in its center; as a result, the x-component of the electric field vanishes obliterating Purcell effect. Here, we consider different geometry, in which both components have almost the same value due to the lack of symmetry.…”

“…Shifting of dispersion dependence towards lower energy is demonstrated for various 2D and 3D plasmonic metamaterials (MM) [25][26][27][28] , and for layered metamaterials [29][30][31] . It was also shown theoretically and experimentally that in layered metamaterials photonic LDOS can be enhanced [32][33][34][35][36][37][38] leading to a pronounced Purcell effect. These works deal with various aspects of the Purcell effect in metamaterials but are similar since they are always considered the dipole placed at some distance from the interface, which is either arbitrary or dictated by experimental or numerical conditions.…”