BINARY AND MULTILEVEL DIFFRACTIVE LENSES WITH SUBMICROMETER FEATURE SIZES

Binary and multilevel diffractive lenses with submicrometer feature si zes are realized on silicon and galliumphosphide wafers using CAD meth ods, direct write e-beam lithography, reactive ion etching, antireflec tion coating, and wafer dicing. Measurements prove aberration-free ima ging and maximum diffraction efficiencies of 70% for lenses with high numerical aperture (NA) of 0.5. Comparisons to other miniature and mic ro-optical elements are carried out with respect to laser-to-single-mo de-fiber coupling and show the competitive performance of the diffract ive lenses. Arrays for 18-channel parallel receiver modules are fabric ated in on-axis and off-axis versions. Optical crosstalk is estimated.