All-optical logical gates AND, OR, NOT, XNOR and XOR based on metalenses at 1.55 µm

This paper presents a novel approach for high-speed optical logic gates based on metalenses. The logic gates consist of two or three phase-controllable metalenses, which can apply different phases to multiple incident light beams of the same initial phase, converging them to a common focal point. This generates interference, enabling logical operations. The advantages of this work include the flexible phase control capabilities of the metalenses, which break the stringent input-phase requirements typically associated with optical logic devices. Additionally, since light predominantly propagates through air, this enhances information transmission rates. The miniaturization of metalenses also offers a potential pathway for achieving efficient parallel computing. The achievable types of logic gates include AND, OR, NOT, XNOR, and XOR, with theoretical contrast ratio of 39.51 dB (OR), 19.21 dB (AND), 11.45 dB (NOT), 11.54 dB (XNOR), and 14.61 dB (XOR). Due to the identical structure, the bit rate for each logic gate stabilizes between 1.04 and 1.05 Tb/s at a 50 % duty cycle. The excellent performance and rapid transmission speeds validate the feasibility of implementing optical logic gates using metalenses.