Diffraction-Unlimited Plasmonic Nanolaser

Abstract

Up to now, significantly reducing the size of semiconductor lasers in all three dimensions is the ultimate challenge for the development of nanolasers, which is a key component for long-waited on-chip optical communications and computing systems. However, the minimum size of conventional semiconductor lasers utilizing dielectric resonators is governed by the optical diffraction limit (λ/2n)³. Recently, we have published the world’s smallest semiconductor laser [1] based on a new concept in laser feedback mechanism. We report on the low-threshold, continuous-wave operation of a sub-diffraction nanolaser based on surface plasmon amplification by stimulated emission of radiation (spaser ) [2]. The plasmonic nanocavity is formed between an atomically smooth epitaxial silver film and a single optically pumped nanorod consisting of an epitaxial gallium nitride shell and an indium gallium nitride core acting as gain medium.