Influence of mode orientations on power transfer at misaligned fibre connections

We present a theoretical, numerical and experimental study of the power transfer at misaligned connections between multimode fibres, demonstrating that the coupling coefficients between incident and excited modes depend on the orientation of the incident modes with respect to the misalignment direction. Taking into account this parameter we derive simple analytical expressions for the power coupling coefficients. These results, valid for fibres of any index profile, help us to better understand mode propagation phenomena and contribute to more precise power coupling calculations, especially in the case of weakly multimode systems where modal noise is more important.