The Photonics Research and Innovation Flagship (PREIN) is a multi-disciplinary competence cluster focusing on the development of light-based technologies. PREIN is a national network that gathers the cutting-edge expertise in Photonics in Finland, including Tampere University, University of Eastern Finland, Aalto University and VTT research center. PREIN is one of the 6 Finnish Flagships funded by the Academy of Finland. The Flagship programme is a northern fleet of excellent science, successful collaboration and solutions for tomorrow.