Blue laser diodes operating at 450 nm can be used as direct application laser sources due to their special wavelength and high material absorption, making them effective for laser welding and printing. Improving the power and brightness of laser diodes (LDs) is a research hotspot. A fiber-coupled blue laser diode with a core diameter of 220 μm was designed, with an output power exceeding 1000 W. The chip achieved a mean time between failures (MTBF) of over 1293 h, and the laser module had an MTBF of more than 1115 h. These results can support direct application laser systems based on blue fiber-coupled laser diodes.

The 200 μm core diameter fiber-coupled LD was achieved using a “(10+10)+(10+10)” multi-step single-chip configuration. Ten single chips were spatially assembled along the fast axis, with 2 channels spatially stacked along the slow axis. Additionally, polarization beam combining of the 2 channels was performed along the slow axis. In total, 40 single chips were coupled into a 105 μm fiber. To enhance power and brightness, 7×1 pumping fiber beam combining technology was utilized to obtain a 220 μm fiber-coupled LD. To improve the reliability of the LD module, the operating current was set to 2.4 A, even though the COS (chip on submount) could operate at a maximum current of 3 A.

A blue fiber-coupled laser diode with a 220 μm core diameter was successfully developed, achieving a practical output power of 850 W. The module’s reliability was improved through a series of measures including chip derating, redundancy design, optimal design of the opposing optical path, chip burn-in, and reduced humidity in the air surrounding the chip. The electro-optical efficiency of the blue light chips was approximately 38%. After collimation with fast-axis collimators (FAC) and slow-axis collimators (SAC), the efficiency was about 95%. The spatial splicing efficiency (accounting for light blocking and leakage) was approximately 97%, the polarization beam combining efficiency was around 97%, and the fiber coupling efficiency was roughly 97%. Overall, the optical efficiency was approximately 86%, with an overall electro-optical efficiency of about 33%. In addition to using a 7×1 pump combiner for efficient beam combining, a 19×1 pump combiner can also be employed. Using a 55 μm fiber-coupled LD as the input arm or sub-beam of the fiber combiner, this sub-beam adopts the method of “fast-axis spatial splicing + polarization combining,” stacking 10 single emitters in the fast-axis direction with a step difference of 0.38 mm. The focal lengths of the FAC and SAC are 0.3 mm and 9 mm, respectively, while the aspherical focusing lens has a focal length of 8.5 mm.

A 105 μm fiber-coupled LD module was designed and developed based on a spatial splicing method, with a power exceeding 150 W@NA=0.19. Using 7×1 fiber-pumped beam combining technology, a 220 μm fiber-coupled LD was developed, with an output power of 850 W@NA=0.22, which significantly improved the filling ratio and utilization rate of the fiber bundle parameter product. Meanwhile, the reliability of individual chips was enhanced through aging screening, derating, redundant design, optical feedback isolation protection, and reduced ambient humidity. The rated operating current of the chips was reduced from 3 A to 2.4 A, resulting in a chip MTBF of over 1293 h and an 850 W LD module MTBF of more than 1115 h, greatly improving the light source reliability. A series of blue laser effect experiments were conducted using this light source, verifying its practicality. This research provides technical support for the space-based application of a specific laser system and lays a solid foundation for further engineering and practical implementation of high-brightness blue light sources.