Patent ID: 7280729

Claim:
A light-directing conduit, comprising: an inner material through which light migrates; a sheath around the inner material and configured to substantially keep light migrating along a path defined by the inner material; wherein the inner material comprises a matrix having one or more rare earth elements dispersed therein; a total concentration of the one or more rare earth elements within at least a portion of the matrix being at least about 1×10 16 atoms/cm 3 ; and wherein the inner material comprises: a first segment containing a total concentration at least about 1×10 16 atoms/cm 3 of the one or more rare earth elements; and a second segment downstream of the first segment along the path of the light along the inner material, with said second segment containing a total concentration of less than 1×10 15 atoms/cm 3 of the one or more rare earth elements.