Journal of Computational Electronics https://doi.org/10.1007/s10825-018-1243-4 Performance investigation of 120 Gb/s all-optical logic XOR gate using dual-reﬂective semiconductor optical ampliﬁer-based scheme Amer Kotb 1,2 · Kyriakos E. Zoiros 3 · Chunlei Guo 1,4 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Reﬂective semiconductor optical ampliﬁers (RSOAs) use an anti-reﬂective coating on the front facet and a high reﬂectivity coating on the rear facet to produce a higher gain than conventional SOAs. In this paper, this potential is exploited to numerically investigate the ultrafast performance of an all-optical logic XOR gate implemented using a dual-RSOA-based scheme at a data rate of 120 Gb/s. The simulation results demonstrate that the XOR gate is capable of operating at 120 Gb/s with better performance than when using conventional SOAs. Keywords All-optical XOR gate · Reﬂective semiconductor optical ampliﬁer · Quality factor 1 Introduction Modern telecommunication networks are dominated by the unceasing generation, use, and storage of an enormous amount of information. The latter is ubiquitous due to Internet-related services and technological developments such as cloud computing, data centers systems, video on demand, online gaming, and intelligent mobile applications. Employing optical ﬁbers provides a physical medium of huge bandwidth that allows to cope with the continuously increas- ing trafﬁc of broadband services and satisfy the diverse users’ needs. However, the mismatch between ﬁber-based capac- ity and operation speed capability of electronic circuitry results in cumbersome optical-to-electrical-to-optical con- versions with associated increased cost, power consumption, B Amer Kotb amer@ciomp.ac.cn Chunlei Guo guo@optics.rochester.edu 1 The Guo China-US Photonics Laboratory, Changchun Institute of Optics, Fine Mechanics, and Physics, Chinese Academy of Sciences, Changchun 130033, China 2 Department of Physics, Faculty of Science, University of Fayoum, Fayoum 63514, Egypt 3 Lightwave Communications Research Group, Department of Electrical and Computer Engineering, School of Engineering, Democritus University of Thrace, 67100 Xanthi, Greece 4 The Institute of Optics, University of Rochester, Rochester, NY 14627, USA and complexity. This problematic ‘electronic bottleneck’ can be overcome by performing several signal processing tasks entirely in the optical domain, i.e., all-optically (AO), and hence directly at the ultra-high speed optical line rate [1]. In particular, the exclusive disjunction (XOR) gate plays a cat- alytic role in this effort due to its involvement in the execution of numerous signal processing tasks both in fundamental and system-oriented level [2]. The logical operation of this dig- ital gate is such that the outputs are in the ‘true’ state only when the binary content of both inputs differs. Given XOR gate signiﬁcance, various technological approaches, which rely on optical nonlinearities, have been followed for its AO realization [1]. Among them, SOAs, which are active devices having very low reﬂectivity coatings at both their input and output sides, exhibit the attractive fea- tures of strong nonlinearity, compact size, and potential for integration with other optoelectronics devices [3]. For this reason, many demonstrations of all-optical logic XOR gates based on conventional SOAs, either as stand-alone nonlinear elements or incorporated in interferometric conﬁgurations, have been reported in the literature [4–12]. However, SOAs also have slow gain and phase recovery times, which lim- its their signal processing capability to data rates that do not exceed ~ 100 Gb/s and hence cannot follow the upgrades of single-channel data rates into the sub-Tb/s region and beyond [13, 14]. On the other hand, reﬂective semiconduc- tor optical ampliﬁers (RSOAs) are a special type of SOAs with an anti-reﬂective coating on the front facet and a high reﬂectivity coating on the rear facet, as schematically shown 123