Self-supporting 2-core butterfly optical cable

A 2-core self-supporting butterfly optical cable features a central bend-insensitive single-mode fiber, flanked by parallel strength members, with a low-smoke, halogen-free sheath suitable for both indoor and aerial outdoor FTTH deployment.

Structure and Design

The cable has a flat, wing-shaped (butterfly) cross-section, with the optical fiber positioned in the center and two parallel strength members on either side. For self-supporting outdoor versions, these strength members can be steel wires or non-metallic FRP (Fiber Reinforced Plastic), allowing the cable to span aerial distances without additional support . The outer sheath is typically LSZH (Low Smoke Zero Halogen) or PE for UV and moisture resistance, providing flame retardancy and environmental protection .

Fiber Type

Most 2-core butterfly cables use bend-insensitive single-mode fiber, conforming to ITU-T G.657 standards. G.657.A1 fibers tolerate small bend radii (~10 mm), while G.657.A2 fibers are suitable for tighter bends in conduit or irregular surfaces, making them ideal for FTTH drop applications . This ensures minimal signal loss even in tight indoor routing.

Key Features

• Small diameter and lightweight, simplifying installation in residential or commercial buildings .
• High flexibility and small bending radius, suitable for indoor wiring and complex routing .
• Good compressive, tensile, and anti-aging properties, ensuring durability over time .
• Bow-type or '8' groove design for easy sheath peeling and maintenance .
• Self-supporting aerial capability for outdoor deployment up to 50 meters without additional support .

Applications

• FTTH networks: from distribution boxes to subscriber terminals.
• Indoor wiring: apartments, residential areas, and office buildings.
• Outdoor aerial drops: connecting poles to building entry points.
• Old area reconstruction or areas with limited conduit space .

Installation Considerations

• Maintain the flat plane orientation during bends to minimize stress on the fiber core .
• Avoid bending edge-on, which requires more force and could damage the fiber.
• For mixed indoor/outdoor runs, either use a dual-rated cable or terminate outdoor sections at wall entry points to splice with indoor drops .

Summary

A 2-core self-supporting butterfly optical cable combines bend-insensitive G.657 fiber, parallel FRP or steel strength members, and a flame-retardant LSZH or PE sheath, making it ideal for FTTH indoor and aerial outdoor applications. Its design ensures easy installation, durability, and minimal signal loss, even in tight bends or complex routing environments .