The best splicers offer core alignment, fast splice times, durable designs, and smart features like cloud syncing and automated calibration. A fusion splicer is a device that joins two optical fibers end-to-end by melting them together using an electric arc. Top-rated models. Fiber optic splicing involves joining two fiber optic cables to create a continuous optical path. Splicing is typically required during cable installation, maintenance, or network expansion. They are perfect for high-performance installations where low loss.