Indoor Introduction to Butterfly-Shaped Optical Cables

Indoor butterfly-shaped optical cables generally use bend-insensitive single-mode fibers with FRP reinforcement and an LSZH sheath.

Core Structure

Indoor butterfly cables feature a flat, wing-shaped cross-section with the optical fiber positioned at the center and two parallel strength members on either side, giving the cable its distinctive butterfly appearance . This design allows the cable to bend easily along the flat plane while resisting sharp kinks, which protects the fiber core during installation .

Fiber Type

These cables almost universally use bend-insensitive single-mode fibers, typically conforming to the ITU-T G.657 standard. For most indoor applications, G.657.A1 fibers are preferred because they tolerate tight bend radii (around 10 mm) and are compatible with legacy G.652.D infrastructure .

Reinforcement

The strength members are usually made of Fiber Reinforced Plastic (FRP), which is non-metallic, providing immunity to electromagnetic interference and eliminating lightning risks . Some variants may use metal reinforcement for additional tensile strength, but indoor-only cables typically rely solely on FRP .

Sheath Material

The outer sheath is commonly LSZH (Low Smoke Zero Halogen), which ensures compliance with fire safety standards for indoor environments. This material is lightweight, flexible, and resistant to environmental factors such as temperature, moisture, and vibration .

Advantages

• Compact and flexible, ideal for tight indoor spaces like data centers or residential buildings .
• High-speed data transmission, supporting large bandwidths up to 100 Gbps .
• Electromagnetic interference resistance, allowing installation near electrical equipment without signal degradation .
• Durable and long-lasting, with reduced maintenance requirements .

Typical Applications

Indoor butterfly cables are used for fiber-to-the-home (FTTH) deployments, data centers, telecommunications, and other indoor networking scenarios where space efficiency, flexibility, and high data rates are critical . They are designed to run from building entry points to subscriber equipment or network racks, often in risers or along walls. In summary, indoor butterfly-shaped optical cables are engineered for safe, flexible, and high-performance indoor fiber installations, combining bend-insensitive single-mode fibers, FRP reinforcement, and LSZH sheathing to meet both mechanical and fire safety requirements .