Loss in multimode fiber connections with a gape

The efficiency and loss of multimode fiber connections are calculated. Use is made of a phase space description of the light rays. The method is valid for small as well as large gaps and both step-index and graded-index fibers. Moreover uniform power distribution and steady-state distribution are both analyzed. The efficiency for all these cases has been calculated and is presented in the form of plots. Simple approximations for small gaps have been derived and compared to other misalignments as radial and angular offset. It appears that the gap gives less loss than the other two misalignments.