Full length article All-optical XOR, NOR, and NAND logic functions with parallel semiconductor optical amplifier-based Mach-Zehnder interferometer modules Amer Kotb a,b,⇑ , Kyriakos E. Zoiros c , Chunlei Guo a,d,⇑ a The Guo China-US Photonics Laboratory, Changchun Institute of Optics, Fine Mechanics, and Physics, Chinese Academy of Sciences, Changchun 130033, China b Department of Physics, Faculty of Science, University of Fayoum, Fayoum 63514, Egypt c Lightwave Communications Research Group, Department of Electrical and Computer Engineering, School of Engineering, Democritus University of Thrace, Xanthi 67100, Greece d The Institute of Optics, University of Rochester, Rochester, NY 14627, USA article info Article history: Received 16 April 2018 Received in revised form 14 June 2018 Accepted 12 July 2018 Keywords: All-optical XOR gate All-optical NOR gate All-optical NAND gate Semiconductor optical amplifier Mach-Zehnder interferometer abstract The performance of XOR, NOR, and NAND functions implemented all-optically (AO) using two parallel semiconductor optical amplifier (SOA)-based Mach-Zehnder interferometers is simulated and investi- gated. The dependence of the quality factor on key input signals and SOAs parameters is investigated and assessed. The obtained results show that the target AO Boolean functions can simultaneously be real- ized with the employed scheme with both logical correctness and high quality at 80 Gb/s. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction A key requirement in the effort to manipulate information at a fundamental and system-oriented level entirely in the optical domain, i.e. all-optically (AO), and hence avoid cumbersome optical-to-electrical-to-optical conversions is the ability to execute Boolean functions exclusively by means of light between data modulated signals at ultrafast line rates [1]. Among these func- tions, the XOR, NOR, and NAND are particularly distinguished due to the special role that they play in the design and realization of AO circuits and subsystems of enhanced logic functionality. More specifically, the XOR function is decisively involved in indis- pensable AO digital processing [2] and arithmetic [3] tasks. The NOR and the NAND are universal functions by repeated use of which it is possible to synthesize any Boolean function and hence construct any digital circuit [4]. Among various technological approaches that have been proposed for the AO implementation of these core Boolean functions, those that rely on semiconductor optical amplifiers (SOA) have been widely adopted [5] owing to these devices’ attractive features of signal amplification, similar to other existing alternatives [6], wide gain bandwidth, strong non- linearity, reasonable switching energy, low power consumption, compact structure, and proven integration potential. At the same time, it is desirable from a practical perspective to perform all these three functions simultaneously without changing each time the switching module and the way it is configured or driven, so as to enable flexible, smart, reliable and repeatable operation, opti- mum use of hardware resources, reduced cost and complexity, for- mation of programmable gate units and arrays, construction of large multi-port switch fabrics as well as of multistage architec- tures and advanced degree of transparency and intelligence at the optical layer [7]. The achievement of this reconfigurability has been pursued based on SOAs either alone, in conjunction with optical filters, or by incorporating them in an interferometric arrangement. More specifically, in the first case [8], the cross- gain modulation (XGM) effect is exploited in multiple SOA replicas, which are suitably interconnected to obtain the AO XOR, NAND and NOR logic functions. However, XGM suffers from high induced chirp and relatively low output contrast ratio, which deteriorates the quality of the logical outcome, especially when the latter must be combined with another one obtained in a similar fashion. In the second case [9], several carefully detuned filters of identical pass- band shape, slope, and width are concurrently employed at the https://doi.org/10.1016/j.optlastec.2018.07.027 0030-3992/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding authors at: The Guo China-US Photonics Laboratory, Changchun Institute of Optics, Fine Mechanics, and Physics, Chinese Academy of Sciences, Changchun 130033, China. E-mail addresses: amer@ciomp.ac.cn (A. Kotb), guo@optics.rochester.edu (C. Guo). Optics and Laser Technology 108 (2018) 426–433 Contents lists available at ScienceDirect Optics and Laser Technology journal homepage: www.elsevier.com/locate/optlastec