Indoor Two-Core Drop Optical Cable Structure

An indoor two-core drop optical cable typically features a butterfly or flat figure-8 design with two parallel FRP reinforcements, a central optical fiber unit, and an LSZH outer sheath for safe, flexible indoor FTTH deployment.

Cable Structure and Components

Core Fiber Unit: The optical fibers are positioned at the geometric center of the cable, usually using G. 657A1 or G. 657A2 singlemode fibers, which are bend-insensitive and suitable for small-radius bends, ensuring high bandwidth and minimal signal loss in tight indoor spaces ( ).

Reinforcement Members: Two parallel Fiber Reinforced Plastic (FRP) rods are placed on either side of the fiber unit. These provide tensile strength, compression resistance, and protection against electromagnetic interference, while avoiding the safety risks associated with metallic reinforcements indoors ( ). Outer Sheath: The cable is encased in a Low-Smoke Zero-Halogen (LSZH) sheath, which is flame-retardant, environmentally friendly, and safe for indoor use.

The sheath can be black or white and is designed for easy handling and installation ( ). Design Form: The cable often adopts a butterfly-shaped flat or figure-8 profile, which simplifies peeling, splicing, and routing through conduits or along walls. This design also allows for flexibility in horizontal and vertical indoor wiring ( ).

Key Features and Advantages

Bend Radius: Supports a minimum design radius as small as 7. 5 mm, making it ideal for tight indoor corners and conduit installations ( ).

Non-

Metallic Reinforcement: FRP members provide lightning protection and reduce the risk of electrical hazards indoors ( ). Lightweight and Practical: The simple structure ensures easy handling, installation, and maintenance ( ). Compatibility: Can be terminated with various field connectors and is suitable for direct cabling to end-user equipment in FTTH networks ( ).

Applications

Indoor two-core drop cables are primarily used in FTTH networks to connect the optical distribution network (ODN) to subscriber premises. They are suitable for horizontal and vertical indoor wiring, including apartments, offices, and enterprise environments, where flexibility, safety, and small bending radius are critical ( ). This structure ensures high mechanical performance, fiber protection, and low installation cost, making it a standard choice for modern indoor fiber optic deployments.