DOUBLE-CLAD FIBRE DOPED WITH RARE EARTH AND PREPARATION METHOD THEREFOR

Disclosed is a double-clad fibre doped with rare earth, comprising a fibre core doped with rare earth ions, an inner cladding and an outer cladding, wherein the cross section of the inner cladding is a non-circular plane including at least two bow-shaped notches. The optical fibre can perform optical machining on a preform without changing a preform preparation process and a fibre-drawing process. The cross section of the inner cladding is designed to be a non-circular plane structure including at least two bow-shaped notches, such that while maintaining the same cladding pump-light absorbing efficiency, a preform grinding process can be simplified, and the rate of breakage due to multi-face grinding of a preform, and the risk of being polluted by machining impurities are reduced, thereby facilitating fibre drawing and the control of precision, and improving the comprehensive performance of an optical fibre.