The primary type of outdoor single-mode optical cable is OS2, designed for long-distance, high-bandwidth transmission with low attenuation.

Key Characteristics

OS2 single-mode fiber is optimized for outdoor and long-haul applications. It has a core diameter of 9 microns, allowing only a single light mode to propagate, which minimizes signal dispersion and supports high-speed data transmission over long distances . OS2 cables typically have a maximum attenuation of 0.3 dB/km at wavelengths of 1310 nm and 1550 nm, enabling transmission distances of up to 40 kilometers without signal amplification . This makes them ideal for telecom backbones, metro networks, and undersea or aerial deployments.

Construction for Outdoor Use

Outdoor single-mode cables are usually built with loose-tube construction, where fibers are housed in gel-filled or dry tubes to protect against moisture, temperature fluctuations, and mechanical stress . The outer jacket is often made of UV-resistant polyethylene (PE) or other rugged materials to withstand environmental exposure. Some variants include armored layers for rodent protection or direct burial applications.

Standards and Variants

• G.652.D: The most common standard for outdoor single-mode fiber, supporting both current GPON networks and future DWDM systems .
• G.657: A bend-insensitive variant suitable for aerial or duct installations where tight bends may occur.
• OS1 vs OS2: OS1 is typically used indoors with tight-buffered construction and shorter distances (up to 10 km), while OS2 is optimized for outdoor, long-distance use .

Applications

Outdoor single-mode cables are widely used in:

• Long-haul telecom networks
• Metro and regional networks
• Fiber-to-the-home (FTTH) backbones
• 5G fronthaul and high-speed data center interconnects Summary: If you are dealing with an outdoor single-mode optical cable, it is most likely an OS2 type, built with loose-tube construction, low attenuation, and designed for long-distance, high-bandwidth transmission in harsh environmental conditions .