COUPLING BETWEEN FREE SPACE AND OPTICAL WAVEGUIDE USING ETCHED COUPLING SURFACES

摘要

A plasma-based etching process is used to specifically shape the endface of anoptical substrate supporting an opticalwaveguide into a contoured facet which will improve coupling efficiencybetween the waveguide and a free space optical signal. Theability to use standard photolithographic techniques to pattern and etch theoptical endface facet allows for virtually any desired facetgeometry to be formed - and replicated across the surface of a wafer for theentire group of assemblies being fabricated. A lens maybe etched into the endface using a properly-defined photolithographic mask,with the focal point of the lens selected with respect tothe parameters of the optical waveguide and the propagating free space signal.Alternatively, an angled facet may be formed alongthe endface, with the angle sufficient to re-direct reflected/scatteredsignals away from the optical axis.