Modal characterization of fiber-to-fiber coupling processes

We present a detailed investigation of a fiber-to-fiber coupling process by characterizing the mode con-tent at the output of the system. In our experiment a single mode fiber is transversally scanned with respect to a multi-mode fiber revealing position dependent higher order mode excitation. The outlined measurement system can be used for automated optimization of fundamental mode content and beam quality and is hence of high relevance for the conception of fiber laser systems.