High-power and brightness 105-micron fiber coupled blue laser diode modules (Conference Presentation)

Efficient laser processing of high reflective materials, such as copper and gold, requires shorter wavelengths than those currently used for high power industrial applications, with blue being the optimal choice. However, the limited power of currently available blue laser chips poses important challenges in scaling the power to the required hundreds of watts while preserving the highest possible beam quality. The paper presents a new proprietary patent-pending architecture that allows achieving world record blue laser brilliance using commercially available high power lasers in TO9 package. The developed architecture is based on single emitters for best flexibility and reliability, which are organized in rows staggered along the fast axis; each row can then be placed side by side to other rows in order to spatially multiplex also along the slow axis. The optimized design gave a final architecture based on 3 rows for a total of 36 emitters that could be coupled into a 105 µm / 0.22 NA. Exploiting also polarization multiplexing and using commercially available 3.5 W diodes it is possible to obtain 220 W of coupled power into a 105 µm / 0.22 NA fiber, for a record brilliance of 150 GW/(ster m2). Following an accurate design phase some prototypes have been fabricated and characterized. Detailed results are presented at the Conference.