Graded-index characteristics in single-crystal fibers

Single-crystal fibers of Ti3+:Al2O3 have been grown by the laser-heated pedestal growth technique and shown to exhibit radial refractive-index gradients. A refractive-index increase of approximately 12% in the fiber core with respect to the fiber sidewalls has been measured. The index profile can be fitted with a parabolic model. Postgrowth treatment of Cr3+:Gd3Sc2Al3O12 fibers has been shown to produce a uniform cladding region with a graded-index core. The core index is some 12.5% larger than the cladding region, with an index profile shape that is approximately parabolic in nature. (C) 1998 Optical Society of America.