A method for designing achromatic hybrid refractive-diffractive elements that can produce beams with long focal depths while they preserve the entire aperture for capture of light and high transverse resolution is presented. Its working principle is based on the combination of a diffractive optical element that generates a long range of pseudonondiffractive rays and a refractive lens of opposite dispersion to form an achromatic hybrid lens. A hybrid lens with a fast f-number (f/1) that works in the entire visible wave band (400-700 nm) was designed and fabricated. Simulation results demonstrate a factor-of-10 improvement in depth of focus compared with that of a conventional f/1 lens, with matching 1-microm lateral resolution. Experimental results confirm the effectiveness of the proposed method through demonstration of an achromatic hybrid lens with better than a factor-of-7 improvement in depth of focus and 1-microm transverse resolution.

We report on the analysis and optimization of a binary phase element for shaping a Gaussian laser beam to a flat-top beam. Simulation results indicate that a single-zone binary phase plate can achieve excellent flat-top beam shaping quality similar to that achieved by using multiple zones. The degradation of flat-top beam shaping quality due to etching depth errors, deviation of illuminating wavelength from design value, and variation of input beam size can be compensated to some extent through on-axis adjustment of the flat-top beam observation plane. Experiments verify these theoretical expectations. The increased beam shaper fabrication tolerance can be greatly beneficial for low-cost prototyping and production of flat-top beam shapers.

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A flexible array waveguide evanescent coupler for card-to-backplane optical interconnects is presented. The proposed technique eliminates traditional 90 degrees out-of-plane turns and local waveguide termination of multidrop bus architectures that hinder conventional card-to-backplane optical interconnections. Evanescent coupling between array waveguide ribbons has been successfully demonstrated. Further experiments have been performed to quantify array waveguide coupling length versus transfer efficiency and waveguide misalignment tolerance. Preliminary optical interconnect testing has demonstrated 2.5GHz operation of the coupler ribbons. The successful high-speed coupling confirms the effectiveness of the proposed method for high-speed computing systems.