An optically nonisotropic composite material. The composite material includes two materials, a transparent bulk optical material and radiation absorbing or reflecting fibers embedded within the bulk material. The fibers are substantially parallel to one another and tend to channel the radiation along the direction of the fibers. The bulk material may be a scintillator, in which case the fibers will tend to channel scintillating radiation along the direction of the fibers. The composite material may be used in a high spatial resolution x-ray device, such as a CT scanner. The composite material may also be used in an electromagnetic radiation detection device. Advantageously, the fibers tend to channel radiation along the fibers towards photodetector cells of the radiation detection device thereby increasing spatial resolution. The composite material may be made by forming powder around sacrificial fibers and isostatic pressing, followed by removing the sacrificial fibers, sintering to form a transparent bulk material with holes, and then filling the holes with the reflecting or absorbing fiber material.