The German Federal Ministry of Education and Research (BMBF) has launched Project DioHELIOS, part of its Fusion 2040 – Research on the Way to the Fusion Power Plant funding initiative. The three-year joint project, funded with €17.3 million (~$19 million), aims to advance high-power laser diodes for fusion power plants, which the German government expects to be built as early as the 2040s. Project DioHELIOS brings together ams-OSRAM, the Ferdinand-Braun-Institut (FBH), Leibniz-Institut für Höchstfrequenztechnik (FBH), the Fraunhofer Institute for Laser Technology ILT, Jenoptik, Laserline, and TRUMPF to boost the power and efficiency of high-power laser diodes and develop approaches for their automated mass production in order to meet the high quantities required to enable energy generation through laser-based inertial confinement fusion. Artist’s rendering of a diode laser module with beam shaping for pumping plate stack amplifiers in high-energy lasers. Such diode laser pump modules are considered a key component for fusion power plants of the future. Courtesy of Fraunhofer ILT. The project is targeting increases in pulse efficiency by a factor of 50 along with simultaneous improvements in efficiency. Further, significantly more homogeneous and stable spectral properties are required, as are diode laser modules that can be mass produced in an automated process at a cost of less than one cent per watt of power. Additionally, the hardware should function for around 30 years at repetition rates of around 15 hz. Over the course of the project, Laserline and TRUMPF will each build different pump modules that will pump a high-energy laser in an initial demonstrator. The consortium is aiming to push diode laser-based pump modules into the megawatt range Jenoptik, ams-OSRAM, and FBH will contribute their expertise as leading manufacturers and developers of laser diodes and drive forward new approaches for semiconductor lasers. Fraunhofer ILT will support them by designing and optimizing the diode laser bars with its specially developed SEMSIS software. The aim is to significantly increase the output power of the chips while ensuring they can be manufactured industrially at the required cost level and resource efficiency. In the case of diode lasers for fusion power plants, the spectral distribution of the laser beam needs to be as stable as possible. The consortium is pursuing new design approaches for this as well as for increased light yield by using so-called multi-junction concepts. They aim to significantly increase the yield in the electro-optical conversion of electrons into photons by stacking several active regions. The optimized diode laser chips will be sent to TRUMPF, Laserline, and Jenoptik, who will use them to build diode laser stacks with a high packing density and consequently high irradiance. Highly effective cooling is particularly important to ensure long lifetime and avoid temperature-induced spectral drifts. The diode laser stacks will serve as building blocks for the pump modules, in which the stacks are arranged in two-dimensional arrays. In addition, the project partners are investigating the potential to optimize the current drivers, which should provide current pulses of more than 1,000 amperes with as little loss as possible. Beam shaping and beam guidance are also on the agenda: Fraunhofer ILT is developing specially optimized optics suitable for automated assembly to collimate and homogenize the beam profile. The partners will then determine how scalable the modules are to higher outputs and pulse energies, and will also evaluate systematic cost control.