GYFTY [non-metallic reinforcing member, loose-layer twisted-filled, polyethylene-sheathed communication outdoor optical cable] The structure of the optical cable is to insert a single-mode or multi-mode optical fiber into a loose tube made of high-modulus plastic and filled with a waterproof compound. Among them, the center of the cable core is a non-metallic strength member. For some fiber optic cables, the non-metallic center strength member is extruded with a layer of polyethylene. The loose tube (and filling rope) is twisted around the central strength member to form a compact and round cable core, the gap in the cable core is filled with water blocking compound and the polyethylene sheath is extruded to form a cable.