How to Make an Optical Fiber Patch Cord

An optical fiber patch cord is a critical component used in fiber optic networks to connect different devices for signal transmission. These patch cords are factory-terminated and tested to ensure high performance and low signal loss. However, with the right equipment and technical know-how, they can also be made manually in a controlled environment. The process of making a fiber optic patch cord involves precision, cleanliness, and the right materials.

1. Materials and Tools Needed

Before beginning the manufacturing process, it’s essential to gather the proper materials and tools:

Materials:

• Fiber optic cable (single-mode or multi-mode)

• Fiber optic connectors (e.g., SC, LC, ST, FC)

• Epoxy or quick-cure adhesive

• Heat shrink tubing or boots

• Ferrules (usually ceramic)

Tools:

• Fiber optic cleaver

• Fiber optic stripper

• Crimping tool

• Polishing machine or hand-polishing kit

• Microscope or fiber inspection scope

• UV curing oven (if using UV epoxy)

• Fiber insertion and curing jig

2. Preparation of the Fiber Cable

The first step in making a patch cord is preparing the fiber cable:

• Measure and Cut: Cut the fiber cable to the desired length using a cable cutter.

• Strip the Cable: Remove the outer jacket using a fiber optic stripper, exposing the buffer tube and aramid yarn (Kevlar).

• Clean the Fiber: Use isopropyl alcohol and lint-free wipes to clean the exposed fiber to remove any residue.

3. Connector Assembly

Next, the connector is prepared and attached:

• Prepare the Connector: Slide the boot and crimp sleeve onto the cable.

• Apply Epoxy: Inject epoxy or adhesive into the connector ferrule using a syringe.

• Insert the Fiber: Gently insert the stripped fiber into the ferrule until it protrudes slightly from the tip.

• Cure the Epoxy: Place the connector in a curing oven (UV or thermal) to harden the epoxy. The curing time depends on the adhesive used.

4. Cleaving and Polishing

After the adhesive has cured, the fiber must be cleaved and polished:

• Cleaving: Use a fiber cleaver to trim the protruding fiber as close as possible to the ferrule tip.

• Polishing: Polish the end-face of the connector using polishing films and a polishing puck. This step is crucial to minimize signal loss (insertion loss) and return loss.

• Inspect the End-Face: Use a fiber inspection microscope to check for scratches, cracks, or dirt. A clean and smooth finish is essential for performance.

5. Final Assembly and Testing

Once both ends of the patch cord are terminated and polished:

• Crimp the Connector: Secure the connector to the cable using a crimping tool.

• Slide and Fit the Boot: Position the boot to protect the connector and provide strain relief.

• Labeling (optional): Label the patch cord if necessary for inventory or installation reference.

• Test the Patch Cord: Use an optical power meter and light source or an OTDR (Optical Time Domain Reflectometer) to test insertion loss and return loss. Industry standards typically require insertion loss to be less than 0.3 dB for single-mode and 0.5 dB for multimode fiber.

Conclusion

Making an optical fiber patch cord is a meticulous process that requires precision, cleanliness, and specialized tools. While mass production is often handled in manufacturing facilities under stringent quality control, understanding the manual process provides valuable insight into fiber optic technology. Properly made patch cords ensure reliable and high-speed data transmission, which is fundamental to modern communication networks.