Plasmonics stems from the surface charge density oscillations at metal–dielectric interface, leading to extremely strong light–matter interactions. In the past few decades, plasmonics has become one of the most favorite fields/techniques in realizing high-performance photonic devices. For this purpose, different new concepts, such as exploration of different radiation frequency regions, two-dimensional materials/heterostructures, and different types of substrates for the excitation of plasmons have been investigated for plasmonics-based sensors and detectors. This book focuses on the recent and advanced works on optical sensors and detectors utilizing plasmonic techniques for opto-electronic applications. The book is unique as it describes both sensors and detectors based on plasmonics and their practical applications in a single book, a feature not found in any book so far.