Comparison of two modal decomposition techniques

Higher oder modes in multi mode fibers determine fundamental beam properties. Hence, the knowledge about the modal content becomes essential to understand the underlying physical effects. Therefore, different modal decomposition techniques have been developed. In this paper we present a comparison of two methods. At first the modal decomposition by a correlation filter method (CFM) and secondly using a numerical phase retrieval algorithm. Limitations of both techniques are demonstrated and theirs overcoming by combining both is presented.