design, fabrication, and optical gain performance of the gain-guided and index-antiguided (gg-iag) fiber are studied systematically in this work. the main parameters of the gg-iag fiber, i.e., a,triangle n, g, and eta, are designed by single-mode operation theories, followed by a detailed study of the fabrication of the gg-iag fiber, including preform design and fabrication, fiber-drawing conditions, and so on. gg-iag fibers with different core diameters (100-380 mu m) are obtained and their corresponding performance is measured. in order to verify whether the parameters of the fabricated gg-iag fiber meet the theoretical design, the laser amplifier experiments of the gg-iag fiber and the fabricated gain-guided and index-guided (gg-ig) fiber are both demonstrated. the experimental results show that the net optical gain coefficient of the gg-ig fiber is the sum of the net optical gain coefficient and the leakage loss coefficient of the gg-iag fiber, which indicates that the fabricated gg-iag fiber parameters and performance are consistent with the theoretical design. this work should help further exploration of the gg-iag fiber. (c) 2017 optical society of america