Fiber Optic Splicing Techniques: Mechanical vs Fusion Methods

Fiber Optic Joints

Because a single coil of fiber optic cable rarely exceeds 2 km in length, while the distance between repeaters or central offices can reach 30 to 40 km, joints are required between sections and at connection points.

Manual or Mechanical Joints

Mechanical connections can be permanent or temporary, often used for testing purposes. These produce higher attenuation, typically ranging from 0.20 to 1 dB.

• They are often filled with index-matching gel to improve light continuity.
• They may consist of cylinders with a central hole or trays secured with keys to house the fibers.

Preparation process:

1. Remove approximately 3 cm of the fiber coating.
2. Clean the fiber thoroughly with isopropyl alcohol.
3. Perform a perfectly straight cut of 5 to 6 mm using a specialized diamond-tipped cleaver.

Fusion Splicing

Fusion joints are permanent and performed using manual or automatic splicing machines. After stripping and cleaving the fibers, the cores are aligned and fused using an electric arc between two electrodes. This method produces minimal attenuation, typically between 0.01 and 0.10 dB.

Fiber Splicing Procedure

1. Stripping: Use a special 125-micron stripper to remove approximately 5 cm of the fiber coating.
2. Cleaning: Clean the fiber with soft paper soaked in high-purity isopropyl alcohol.
3. Cleaving: Cut the fiber to 8–16 mm using a diamond-blade cleaver, ensuring the coating end aligns with the measurement mark.
4. Handling: Once cut, do not touch or contaminate the fiber end.
5. Alignment: Place the fiber into the splicer according to the markings. Repeat for the second fiber.
6. Inspection: The machine display will show both fiber ends; if the angle is not perfectly straight, the machine will prevent the splice.
7. Fusion: Once aligned on the Y-axis, the machine applies a pre-fusion arc followed by the final fusion power to join the fibers.