Crosstalk in Multiple-Beam Waveguides

Crosstalk limits the number of communication channels which are spatially resolvable at the end of a beam waveguide. The main sources of crosstalk are scattering and distortion by the focusers. A careful study of high quality front surface mirrors led to the results of this paper. The best choice seems to be a periscopic guide made of dielectric mirrors when used with gaussian beams in a particular mode of multiple transmission. We give a closed description for the expected power profile of a gaussian beam that has passed such a guide and an approximate formula for the mutual crosstalk between several such beams.