Long-term stable fiber-coupling requires sub-micron precision and pointing stability. This is especially true when a polarization-maintaining single mode fiber is to be permanently attached to a free beam laser. These modular, complex and self-contained setups also often increase laser safety and reduce the laser safety classification. Semi-permanent connections can be made with mechanical splices, which are. ngths with coupling eficiencies as high as 80%. Whilst this value is easily achievable when laser light is coupled into multimode fibres, for single-mode fibres, 80% eficiency is close to the theoretical limit, and presents a number of significant challenges especially at powers higher than a few. Accurate analysis of coupling efficiency is critical in the design of fiber coupling systems.