Optical Waveguide Geodesic Lenses.

摘要

The goal of this program was the development of near diffraction-limited optical waveguide geodesic lenses. The means selected for achieving this goal was the formation of corrective waveguide overlays adjacent to spherical-depression lenses. Theoretical analyses of design criteria and fabrication tolerances for these overlays, called corrector plates, were carried out. Measurement techniques for experimentally determining design parameters were developed and implemented, thus minimizing the need for precise knowledge of lens and waveguide characteristics. Depression generation and polishing procedures were varied to enable the fabrication of Ti-diffused LiNbO3 waveguides of high optical quality, albeit at some loss of lens figure. Lenses were evaluated using focal images of prism output-coupled light. Aberrations induced during prism output coupling were taken into account theoretically. In the case of a 55-mm focal-length lens, we observed near diffraction-limited f/19 performance over a full field of view exceeding 1.22 deg. The full width of the central peak was 13.25 micrometers, about 17% above the diffraction-limited value for a 2.9-mm input aperture. The corrector-plate concept was found to be potentially useful in reducing the severe tolerance requirements associated with optical waveguide lens fabrication, and consequently should be an important feature of integrated optical signal-processing systems. (Author)