Tunable Electro- and All-Optical Switch Based on Epsilon-Near-Zero Metasurface

A novel design of a tunable optical switch based on epsilon-near-zero (ENZ) metasurface is proposed, which can work as an electro-optical or an all-optical switch, and be tuned by gate-voltages, incident angles, and intensity of pump light. The result shows that the coupling of the ENZ mode and plasmon resonance lead to an obvious Rabi splitting which can be observed in the transmission spectrum. Numerical analysis also demonstrates that the coupling belongs to the ultra-strong coupling regime. The proposed design can achieve electro-optical switching with a large modulation depth of up to ~ 17 dB, all-optical switching with an extinction ratio exceeding 5 dB and an ultrafast response time of 650 fs.