Perspectives on the orbital angular momentum of light

Orbital angular momentum (OAM) has been known and understood in mechanical systems for centuries, but far less venerable in optical systems. It was only 30 years ago that OAM was directly associated with the spatial structure of light, specifically its phase structure, allowing OAM carrying light to be routinely created in optical laboratories. The explosion in activity since then has been startling, with OAM finding applications in microscopy, imaging, metrology and sensing, optical trapping and tweezing, communication and quantum science. Many of these advances have been reported in this very journal, and so it is fitting that the Journal of Optics should have a special issue dedicated to the topic, celebrating 30 years of advances with a collection that includes original work, reviews and tutorials, covering the past, present while pointing to an exciting future.