Fiber optic patch cords are best made with glass or plastic cores, aramid (Kevlar) strength members, and jackets such as LSZH, PVC, or plenum-rated materials depending on the installation environment.

Core and Cladding Materials

The core of a fiber optic patch cord is typically made of high-purity glass for single-mode or multimode fibers, providing low signal loss and high bandwidth over long distances. Plastic cores are sometimes used for short-distance or cost-sensitive applications. Surrounding the core is the cladding, also made of glass or plastic, which reflects light back into the core to maintain signal integrity and prevent leakage .

Strength Members

To enhance durability and prevent breakage, patch cords include strength members, usually made of aramid yarn (Kevlar). This material provides tensile strength without compromising flexibility, allowing the cable to withstand pulling, bending, and handling during installation .

Jacket Materials

The outer jacket protects the fiber from environmental hazards and mechanical damage. Common materials include:

• LSZH (Low Smoke Zero Halogen): Produces minimal smoke and no toxic halogens in case of fire, making it ideal for indoor environments like data centers, offices, and buildings where safety regulations apply .
• PVC (Polyvinyl Chloride): Suitable for basic indoor use but not recommended for air ducts or plenum spaces .
• Plenum-rated (OFNP): Fire-resistant and safe for air ducts, required in many commercial installations .

Specialized Options

• Bend-insensitive fibers: Reduce signal loss in tight bends, useful in high-density racks or constrained spaces .
• Armored cables: Include a metallic layer for protection against crushing or rodent damage, suitable for industrial or outdoor environments .
• Mode-conditioning cables: Help equalize optical paths when using multimode fibers with single-mode equipment .

Summary

For most applications, a glass core with Kevlar strength members and an LSZH jacket is considered the best combination for indoor, high-density, and safety-conscious environments. For outdoor or industrial use, armored jackets or plenum-rated materials may be preferred. Choosing the right materials ensures signal integrity, durability, and compliance with safety standards .