A compact plasmonic MOS‐based 2×2 electro‐optic switch

We report on a three‐waveguide electro‐optic switch for compact photonic integrated circuits and data routing applications. The device features a plasmonic metal‐oxide‐semiconductor (MOS) mode for enhanced light‐matter‐interactions. The switching mechanism originates from a capacitor‐like design where the refractive index of the active medium, indium‐tin‐oxide, is altered via shifting the plasma frequency due to carrier accumulation inside the waveguide‐based MOS structure. This light manipulation mechanism controls the transmission direction of transverse magnetic polarized light into either a CROSS or BAR waveguide port. The extinction ratio of 18 (7) dB for the CROSS (BAR) state, respectively, is achieved via a gating voltage bias. The ultrafast broadband fJ/bit device allows for seamless integration with silicon‐on‐insulator platforms for low‐cost manufacturing.