The structure of the buried optical cable is to insert a 250 μm optical fiber into a loose tube made of a high modulus material, and the loose tube is filled with a waterproof compound. The center of the core is a metal reinforced core. For some cores, the metal reinforced core needs to be extruded with a layer of polyethylene (PE). The loose tube (and the filling rope) is twisted around the center reinforcing core into a compact and round core, and the gap in the core is filled with a water blocking filler. After the plastic coated aluminum strip (APL) is longitudinally wrapped, a polyethylene inner sheath is extruded, and the double-sided coated steel strip (PSP) is longitudinally wrapped and extruded into a polyethylene sheath to form a cable.
