Diffractional crosstalk in beam waveguides for multibeam transmission

A discussion is presented on diffractional crosstalk which occurs when several Gaussian beams of approximately the same frequency are transmitted simultaneously through a beam waveguide with oversized lenses. The diffractional crosstalk arises from beam coupling caused by aperture diffraction. Theoretical results indicate that this coupling effect is very small. Simultaneous transmission of 16 Gaussian beams at λ = 0.6328 µ through a guide with lenses of only 5 cm diameter and a lens spacing of 100 m could be performed with a diffractional crosstalk levd below -60 dB in each channel even for distances greater than 1000 km.