A method of designing multicore optical fibers is provided. A geometry for the core arrangement is selected. At least one of i) core width, ii) core position with respect to other cores, or iii) orientation with respect to incoming, outgoing, or at least partially traversing radiation such as an inscription beam are optimized. A design space is created in which no core shadows or blocks any other core with respect to incoming, outgoing, or at least partially traversing radiation. Optimization generally includes tracing tangents of core widths against an orthogonal axis and ensuring no overlap of space between said tangents on said axis. For twisted fiber, optimization also includes optimizing effective length and twist rate of the fiber. Devices entailing such fibers, such as multicore pump coupler and multicore fiber distributed feedback laser, are also contemplated.