Inverse-rib hybrid plasmonic waveguide for low-loss deep sub-wavelength surface plasmon polariton propagation

Abstract

We propose an inverse-rib plasmonic waveguide which is more realistic and easy-to-fabricate to provide a more realistic image of previously proposed waveguides and simplified fabrication processes. It is shown that despite major changes in the structure, this waveguide provides optical properties comparable to previously proposed ones in \(\uplambda =1.55\,\upmu \hbox {m}\) telecommunication wavelength. Characteristic modal area of the designed waveguide reaches below \(\uplambda ^2/3600\) with propagation lengths on the order of several tens of microns. It also offers high Purcell factor ranging from 75 to 145 with figure of merits around \(9\times 10^3\) to \(1.7\times 10^3\). Also studied is the compensation of gain in InGaAsP materials, for which critical gains from 150 to 700 \(\hbox {cm}^{-1}\) are calculated for loss-less waveguiding.