Advances in power-delivery and loss-handling capabilities of small connectors for fibre-optic launching of high-power diode lasers

Constant advancement in laser sources leads to commercial and industrial lasers with ever higher output powers and brilliance. The increasing capabilities of diode laser sources in particular produces extreme challenges for fibre launching. The difficulties arise due to the nature of the diode lasers, which are often designed with a numerical aperture (NA) exceeding the optical fibre's NA and a spot size overfilling the fibre core so as to maintain the best possible brilliance. In addition to these properties, the spot imaged onto the fibre facet is typically rectangular. The combination of these properties result in an imperfect launch efficiency, forcing the connector built around the optical-fibre to cope with the radiation which is "lost" from the core of the fibre. Improvements in the Optoskand SMAQ connector are discussed, along with the presentation of results showing the increased power-and loss-handling capabilities when used with a variety of diode laser sources at 976nm. The sources used in the tests are optimised for an optical-fibre of core diameter (empty set) 200 mu m and NA of 0.22. The sources range in maximum power from 150W to 1000W with a coupling efficiency of between 80 and 90%. Additional complimentary results are shown for a empty set=400 mu m fibre guiding light of NA=0.12 where launch efficiency is 90 to 95%.