4XX nm diode-laser beyond 2 kW of output power

Since the first blue lasers made from GaN-based semiconductors reached power levels making them suitable for industrial applications a few years ago, users where asking for more power. Quickly, output powers for fiber-coupled diode lasers increased from several hundred watts in early 2018 [1] to 1000 W in 2019 [2] and even 2000 W in 2020 [3]. But lifetime has always been an object of concern since the blue diode-laser moved out of the TO-can to enter the high power world. As part of the research project "FoulLas", which started in 2019 and is funded by the German Federal Ministry for Economic Affairs and Energy (BMWi), Laserline took on the task of developing a cw fiber-coupled diode-laser exceeding 2 kW blue laser power for fouling removal of vessels and submarine structures. Caused by stronger restrictions on the use of biocide containing coatings for ship hulls, new strategies against marine fouling moved into the focus of development activities. A new approach is to lethally damage the microorganisms on the subsea surfaces by laser irradiation to be washed away by the streaming water. Apart from that, they can no longer contribute to the spread of species. This paper covers concepts and possibilities of power increase beyond 2 kW for fiber-coupled lasers based on blue diodelaser bars. Results of a laser with more than 2 kW output power are presented. In addition, new findings on degradation processes and lifetime tests are reported. To tie in with the application, insights into the maritime application of fouling removal are given.