Planar Yagi-Uda antennas for highly efficient light extraction and directional light emission

Nanoscale light emitters, such as nanocrystals, organic molecules, and color centers in solids, offer a wide range of opportunities for applications. However, light cannot be easily collected from such systems due to radiation at wide angles and total internal reflection, especially when the refractive index of the host medium is large. Typically, advanced optical nanostructures and/or sophisticated external optics are required to overcome these issues. Recently, we have proposed a planar structure that beams the emission of single molecules [1]. It relies on the concept of an optical Yagi-Uda antenna, where reflector and director elements are implemented using thin metal films. However, surface plasmon polaritons (SPPs) at the interface between the metal films and the dielectric layers can strongly affect the outcoupling efficiency.