This edited book distinguishes itself by providing an in-depth exploration of recent keywords such as photonic crystals, quantum key distribution, and heterogeneous integration. By bridging the gap left by existing literature, the book offers a holistic perspective on optical sensing technologies and distributed sensing networks. It delves into challenges and future directions, particularly focusing on the burgeoning field of quantum sensing technologies. It will provide a thorough examination of innovative techniques, emerging trends, and real-world applications in the field. The book will bring together leading experts and researchers to contribute chapters that cover a wide range of topics, from fundamental principles to cutting-edge advancements. Tailored for researchers, academics, and professionals in the realms of optics, photonics, sensor networks, and related disciplines, this book accommodates a diverse audience. It caters to those seeking foundational knowledge as well as experienced practitioners looking to stay abreast of advanced techniques. With a specific emphasis on wireless sensor networks, environmental monitoring, and applications in opto-electronic materials, this book addresses the interdisciplinary nature of modern sensing technologies.