Outdoor Optical Cable Structure and Technology

An outdoor optical cable is a type of communication line designed for the transmission of optical signals; it consists of a specific number of optical fibers arranged in a particular configuration to form a cable core, which is then encased in a sheath-sometimes with the addition of an outer protective layer.
Its design adheres to the principle of environmental adaptability, specifically the "Three Defenses and Two Resistances": protection against water, moisture, and corrosion, and resistance to tensile and compressive forces. Water protection is achieved through a dual-mechanism design: the cable core prevents water ingress via PBT loose tubes filled with water-blocking gel, while the outer layer ensures a watertight seal through the use of high-density polyethylene (HDPE) or a bonded aluminum-polyethylene sheath. Alternatively, "all-dry" technology employs dry water-blocking materials-such as water-swellable yarns, powders, or tapes-to replace the traditional gel filling.

Mechanical protection is tailored to different installation methods: direct-buried cables utilize steel tape or steel wire armoring to withstand lateral pressure; aerial cables employ a self-supporting "figure-8" structure-potentially equipped with vibration dampers-to enhance their resistance to tensile stress and wind loads; and duct cables typically feature structures such as the central loose tube design, often reinforced with aramid yarns. Biological protection measures include incorporating glass fibers or stainless steel wires into the sheath to deter rodents, or adding anti-termite agents-or utilizing a Nylon 12 sheath-to prevent termite infestation. Temperature adaptability requires the sheath material to retain its flexibility in extremely cold environments-for instance, through the use of low-temperature modified polyethylene sheaths-while also reflecting thermal radiation in high-temperature environments via the incorporation of additives such as carbon black masterbatch.