Optical skyrmions: from fundamentals to applications

Abstract Skyrmions are topologically protected quasi-particles that have aroused substantial interest in nuclear physics and condensed matter physics. For instance, magnetic skyrmions are regarded as having potential applications in high-density information storage due to their ultracompact size, topologically protected stability, and low driven current. Recently, optical analogs have been discovered in light field, known as optical skyrmions. With similar intriguing properties, research on optical skyrmions has grown dramatically. Several types of optical skyrmions defined by various optical parameters have been uncovered. Along with the fundamental physics studies, methods for generating, modifying, and detecting optical skyrmions have also been developed, which in turn enriches the toolkit for light field modulation and detection. It has shown promising applications in high-precision positioning, information storage, and optical communication. In this paper, we begin with the fundamental theory and then introduce generalized classes of optical skyrmions, with a particular emphasis on optical spin skyrmions. We discuss their generation, modulation, and detection methods. Additionally, we highlight the emerging applications of optical skyrmions, showcasing the potential of these unique properties for future advancements.