Fabrication of few-mode crystalline core fiber

A few-mode crystalline core fiber (FMCCF) cladded by high-index glass is demonstrated. The FMCCF consisted of 38-μm core with YAG single crystal and 260-μm cladding with N-SF57 high-index glass, which was fabricated by drawing-tower and laser-heated pedestal growth techniques. The FMCCF exhibited a V-value below four at 1400 nm to provide five few-mode characteristics.