An index-matching gel for use with nano-engineered optical fibers is disclosed. The index-matching gel is cross-linked, which prevents the gel from wicking into the voids and down the nano-engineered optical fiber to a depth where the fiber performance and/or device performance is compromised. The formulation comprises a non-reactive constituent A, two reactive constituents B and C, and a catalyst D. The gel is pre-cured and forms a cross-linked internal network that results in a single-component gel that does not require meter mixing of an additional constituent or heat curing. The gel is suitable for use in the mechanical splicing of optical fibers when at least one of the optical fibers is a nano-engineered optical fiber. The gel is also suitable for use in fiber optic connectors wherein at least one of the optical fibers constituting the connection is a nano-engineered optical fiber.