A simple method for calculating coupling efficiency in optical interconnection system involving various misalignment parameters

A simple method is presented to approximate the coupling efficiency in optical interconnection systems, which are affected by alignment parameters of various optical elements. The method considers geometric effects of alignment parameters, not considering the material-dependent losses which are insensitive to the misalignment parameters. To indicate the independent contribution of a given alignment parameter, we define a partial coupling efficiency (PCE) that reflects the effect of only one parameter on a local coupling efficiency at an optical element. The total coupling efficiency (TCE) in the whole system is approximated by multiplications of the PCEs calculated for each parameter and normalization factors. For an interconnection scheme using a 45°-ended waveguide, we demonstrate by considering many misalignment parameters simultaneously that our approximation is well matched to the results of the simulated TCE.