Method for Increasing the Core Count and Area of High Density Optical Fiber Bundles

Current manufacturing methods limit the increase in both core count and the area for optical fiber bundles. Here a method for increasing the core count and hence the available image area of high density optical fiber bundles, through fusing multiple smaller sized sub-bundles is proposed and experimentally investigated. The key issue being investigated is whether it is possible to eliminate or reduce the dead-space between cylindrical sub-bundles, where no cores are present to spatially sample an image. Small sample lengths of fused optical fiber bundles are fabricated and characterized using an optical and scanning electron microscope to assess the reduction in dead-space and the optical losses near the interfaces. We demonstrate a 30% decrease in the dead-space area through fusing three equally sized sub-bundles in a triangular arrangement, while still retaining the light-guiding ability of more than 70% of the cores which transported into this region. We also assessed the optical losses for cores near the fused interfaces, at different wavelengths in the visible spectrum. A model of the propagation modes supported by the cores is explored which attributes these losses to the increasing eccentricity of cores near the fused interfaces.