Of optical fibers, a splice, i.e., permanent joint, accomplished by aligning the mating fibers in some kind of mechanical fixture. Note 1: The fibers may be secured by mechanical means or with an optical adhesive. Note 2: When the fibers are secured by mechanical means, the gap between them is usually filled with an index-matching gel to reduce Fresnel reflection. Likewise, the optical adhesives that are used in conjunction with mechanical splices are formulated to have a refractive index that approximates that of the glass, and also serve to reduce Fresnel reflection.