Quenching, Plasmonic, and Radiative Decays in Nanogap Emitting Devices

Abstract

By placing a quantum emitter in the mouths of nanogaps consisting of two\nmetal nanoparticles nearly into contact, significant increases in emission rate\nare obtained. This mechanism is central in the design of modern plasmonic\nnanoantennas. However, due to the lack of general knowledge on the balance\nbetween the different decay rates in nanogaps (emission, quenching, and metal\nabsorption), the design of light-emitting devices based on nanogaps is\nperformed in a rather hazardous fashion; general intuitive recipes do not\npresently exist. With accurate and simple closed-form expressions for the\nquenching rate and the decay rate into gap plasmons, we provide a comprehensive\nanalysis of nanogap light emitting devices in the limit of small gap thickness.\nWe disclose that the total decay rate in gap plasmons can largely overcome\nquenching for specifically selected metallic and insulator materials,\nregardless of the gap size. To confront these theoretical predictions, we\nprovide a comprehensive numerical analysis of nanocube-type antennas in the\nlimit of small gap thickness and further provide upper bounds for the\nphoton-radiation efficiency.\n