In this book, we focus on the design of efficient optical switch architectures with reduced complexity to resolve packet contention in asynchronous OPS networks. In particular, the main contributions of this book can be summarized as follows: (1) propose a new FDL-based switch architecture that achieves the same performance as that of best known architectures but with a reduced hardware complexity, (2) conduct a detailed study of the impact and complexity of using WCs in the design of optical switch architectures, and (3) develop and analyze a new hybrid OPS switch architecture that has a smaller packet loss, average switching delay, and hardware complexity compared to exiting optical switch architectures.