Extremely enhanced figure of merit in nonlinear plasmonic waveguides in the C-band using metamaterials and a nonlinear active medium

Abstract

Nonlinear plasmonic waveguides (NPWs) have attracted consideration in the last decade due to the strong light confinement, their peculiar nonlinear effects, and their small footprint [1-3]. Nevertheless, no clear enhancement of the nonlinear figure of merit (FOM) compared with all-dielectric waveguides has been observed yet due to the trade-off between the confinement of the light and the high losses inherent to plasmonic structures [4]. In this work, we propose new NPWs based on an active semiconductor indium gallium arsenide phosphide (InGaAsP) as a nonlinear core material and metamaterial claddings with an isotropic dielectric response for the transverse magnetic polarized (TM) waves (see Fig. 1(a)). Our choice of the InGaAsP as a nonlinear material is based on the three following reasons. First, it has been demonstrated experimentally, that the nonlinear refractive index of InGaAsP can be extremely enhanced if the operating wavelength is close to the band-gap wavelength of the InGaAsP [5] which ensures a high value of the nonlinear refractive index compared to the corresponding value of the two-photon absorption (TPA). Consequently, the general criterion for avoiding large TPA-induced losses [6] is satisfied. Second, InGaAsP can act as a gain medium via electrical or optical pumping [7], this means that it can compensate for the linear losses induced by the metal based metamaterial used in the NPW claddings. Third, it works in the telecommunication C-band.