Single-crystal fibers of Ti<sup>3+</sup>:Al<sub>2</sub>O <sub>3</sub>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 Cr<sup>3+</sup>:Gd<sub>3</sub>Sc <sub>2</sub>Al <sub>3</sub>O<sub>12</sub>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.
© 1998 Optical Society of America
J. H. Sharp, R. Illingworth, and I. S. Ruddock, "Graded-index characteristics in single-crystal fibers," Opt. Lett. 23, 109-110 (1998)