Vol.:(0123456789) Optical and Quantum Electronics ( 2019) 51:154 https://doi.org/10.1007/s11082-019-1874-0 1 3 Design of all‑optical XOR and XNOR logic gates based on Fano resonance in plasmonic ring resonators Marziyeh Moradi 1  · Mohammad Danaie 1  · Ali Asghar Orouji 1 Received: 22 December 2018 / Accepted: 30 April 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract In this paper, compact all-optical XOR and XNOR gates based on diferent confgurations of metal–insulator–metal plasmonic ring resonators (PRRs) have been proposed. Square and octagon-shaped rings have been used in this case. The logic gates have been simu- lated using the two-dimensional fnite-diference time-domain numerical method, with a  conventional perfectly matched layer as the absorbing boundary condition of the area under simulation. The phenomenon of Fano resonance is employed by the proposed gates to excite ON/OFF states. As a result, a large value of contrast ratio (C.R.) is obtained. The results show that the values of C.R. of XNOR and XOR gates for square-shaped PRR are 22.66 and 22.9 dB, respectively and the values of C.R. of XNOR and XOR gates for octagon-shaped PRR are 23.01 and 23.52 dB, respectively. Also, it is shown that the octa- gon-shaped gates have higher transmission ratios than other proposed confgurations. The proposed optical logic gates can be used as key components in optical communications and for designing compact plasmonic devices. Keywords All-optical logic gate · Metal–insulator–metal (MIM) · FDTD method · Plasmonic · Ring resonators (PRRs) · Fano resonance 1 Introduction Surface plasmon polaritons (SPPs) are electromagnetic waves which can propagate at metal–dielectric interfaces (Szunerits and Boukherroub 2015; Wang et al. 2009). It is shown that, SPPs are capable to overcome the conventional difraction limit and con- fne light in nanoscale domains (Veronis et al. 2009). Such a specifcation can be very important for design of highly integrated optical circuits. Although many high qual- ity optical devices such as flters, sensors, logic gates and optical memories can also be implemented using, diferent benchmarks such as photonic crystals (Geravand et al. 2019; Danaie and Kaatuzian 2012; Danaie et al. 2018), or Si-photonics technology, but the footprint of plasmonic devices is far smaller than the mentioned methods (Dan- aie et al. 2008, 2018; Danaee et al. 2019). Furthermore; since plasmonic devices use * Mohammad Danaie danaie@semnan.ac.ir 1 Faculty of Electrical and Computer Engineering, Semnan University, Semnan, Iran