The preparation of GaAs thin-film optical components by molecular beam epitaxy using Si shadow masking technique

In this letter, we further substantiate one of the very important advantages of molecular beam epitaxy (MBE) over liquid-phase epitaxy (LPE) and chemical vapor-phase deposition (CVD), namely, the ability to incorporate shadow masking during epitaxial growth, by fabricating several important thin-film optical components. These include two-dimensional optical waveguide tapered couplers as narrow as 2 μm, optical horns having absolutely featureless mirrorlike surfaces, and waveguide widths in the submicrometer range, and Luneburg lenses having perfect symmetry, extremely smooth surface, and very gentle transition.