Mid-infrared polarization rotator based on a Si3N4-CaF2 hybrid plasmonic waveguide with asymmetric metal claddings

In this paper, a Si3N4-CaF2 hybrid plasmonic waveguide (HPW) with an asymmetric metal cladding is designed for the mid-infrared polarization rotator (PR). The mode characteristics and polarization rotation performances of the Si3N4-CaF2 HPW-based PR are simulated by using the finite element method. Operating at the wavelength of 3.5 mu m, the polarization conversion efficiency between two polarization modes (PM 1 and PM 2) is larger than 99% at a Si3N4- CaF2 HPW length of 10(4) mu m. The Si3N4-CaF2 HPW-based PR maintains good polarization rotation performances within fabrication tolerances from 10 to 10 nm. The polarization rotator based on the Si3N4-CaF2 HPWpaves the way to achieve integrated waveplates, driving many important optical functions from free space onto a chip. (C) 2021 Optical Society of America