Review on all-optical logic gates: design techniques and classifications - heading toward high-speed optical integrated circuits

All-optical logic gates (AO-LGs) are the key elements that play a pivotal role in the development of future all-optical networks and all-optical computing. A complete overview of the seven all-optical logic gates (i.e., AND, OR, NOT, XOR, XNOR, NAND, and NOR) based on their design techniques and applications are covered, including the latest technologies, such as topological photonics and artificial intelligence-based designs techniques. In addition, we have further categorized the AO-LGs as reconfigurable gates, simultaneous gates, reversible gates, modulation-based gates, and data rate-based gates. The techniques to implement these different classes of gates are reviewed and their limitations are discussed. We also discuss in brief the various simulation tools used to design and analyze the AO-LGs. Finally, the most feasible techniques for constructing optical integrated circuits based on the existing fabrication technologies and available resources are explored, and future prospects are outlined. (C) 2022 Society of Photo-Optical Instrumentation Engineers (SPIE)