Heavily Doped Semiconductors for Integrated Nonlinear Plasmonics

The control and the concentration of light at subwavelength scales are of extreme importance for the realization of integrated optical technologies, especially to reach operational efficiencies in devices based on nonlinear optical effects. In this context, the study of light interaction with free electrons (FEs), i.e. plasmonics, in materials characterized by a high carriers density has a central role. Notoriously, noble metals have been the main material choice for plasmonic devices in the visible spectrum for many years. Heavily doped semiconductors (i.e. with charge densities $n_{0}\sim 10^{19}-10^{20}$ cm- ³ ), on the other hand, have recently emerged as alternative materials for plasmonics in the near-infrared (NIR), i.e. $0.8 < \lambda < 2\ \mu \mathrm{m}$ , and in the mid-infrared (MIR), i.e. $2 < \lambda < 20\ \mu \mathrm{m}$ [1]. Being low-loss high-quality materials that can be compatible with standard microelectronics fabrication processes, and being their optical response tunable through electrical or optical doping, heavily doped semiconductors offer a unique perspective for integrated optical devices in the NIR and in the MIR. [2].