Polyurethane fan-out channel waveguide array for high-resolution optical waveguide imaging

A channel waveguide array formed in a fan-out pattern is introduced as a means of enhancing optical waveguide focal plane resolution in integrated optical devices utilizing optical waveguide lenses. High optical resolution is obtained by having light propagating in a thin-film slab waveguide incident on a high-density array of channel waveguides. The width and spacing of these channel waveguides then taper to larger values in a fan-out pattern, eventually terminating at elements of a detector array. High spatial resolution can thus be obtained without making detector spacings too small. This avoids detector problems with regard to fabrication, cross talk, linearity and charge transfer efficiency. To fabricate the fan-out channel waveguide array, a new differential heating and photoresist lift-off process is presented which allows high resolution patterns to be reproducibly formed in polyurethane. Propagation of light from a HeNe laser in these fan-out channel waveguide arrays is demonstrated with only a small amount of scattering. Low scattering is consistent with the smooth channel waveguide surfaces apparent in scanning electron microscope pictures presented.