In the digital age, smart grids stand as the backbone of modern energy systems, facilitating efficient energy distribution and management. However, this sophistication comes at the cost of heightened vulnerability to cyber threats. Standing on the precipice of a hyper-connected future, the inadequacies of current cybersecurity measures loom large, demanding urgent attention from academic scholars and industry experts. 5G and Fiber Optics Security Technologies for Smart Grid Cyber Defense addresses the challenges of securing smart grid systems through communication technologies. The book navigates through 5G wireless and fiber optics, offering a nuanced understanding of their application in the context of grid security. The book begins by exploring the inherent vulnerabilities in smart grid architecture and the imperative role of cybersecurity in modern energy systems. Subsequently, it delves into the specifics of 5G network architectures, dissecting the technologies and standards underpinning the new radio (NR) while emphasizing the significance of network slicing and security isolation. Concurrently, the book unveils the intricacies of fiber optic communication in smart grids, elucidating network design, security measures, and integrating fiber optic sensors for grid monitoring and intrusion detection.