2025 Topical Meeting on Optical Interference Coatings: introduction

This feature issue of <i>Applied Optics</i> presents a curated selection of papers from OIC 2025, the sixteenth Topical Meeting on Optical Interference Coatings (OIC) held May 18-23, 2025, in Tucson, Arizona, USA. The issue celebrates the 50th anniversary of OIC, reflecting the conference's depth and breadth. This triennial meeting serves as a premier international forum for the optical interference coatings community, bringing together researchers, engineers, and industry professionals to present and discuss the latest developments in the field. The meeting showcases cutting-edge advances in coating design theory, innovative materials, deposition and characterization techniques, and a wide array of applications. Topics presented span technologies for green energy, aerospace systems, gravitational wave detection, telecommunications, optical instrumentation, consumer electronics, and high-power and ultrafast laser systems, among others. Beyond the technical sessions, OIC 2025 provided valuable opportunities for collaboration, networking, and the cross-pollination of ideas, continuing its legacy as a cornerstone event in the advancement of optical coating science and technology.