Common Fiber Optic Cold Splices

Mechanical cold splices, including mechanical splice connectors, splice-on connectors (SOC), and fiber optic pigtails, are the most commonly used methods for joining fibers without fusion.

Mechanical Splice Connectors

Mechanical splices are the primary type of cold splice. They use a ferrule and body system to align and hold two fiber ends together precisely. The ferrule secures the fiber, while the body provides structural support and alignment with the mating fiber.

An index-matching gel is often applied inside the splice to reduce light loss and back reflection. These splices are quick to install, require no heat, and are ideal for temporary or field repairs, though they typically have slightly higher insertion loss than fusion splices.

Splice-

On Connectors (SOC)A splice-on connector is a factory-made connector attached to a fiber via a mechanical splice. The bare fiber from the cable is inserted into the SOC, which aligns it with the connector ferrule. This method combines the precision of a factory-terminated connector with the flexibility of field splicing.

SO

Cs are widely used for single-mode fibers in data centers, telecom networks, and FTTH deployments, providing a reliable, low-loss connection without fusion equipment.

Fiber Optic Pigtails

Fiber optic pigtails are short fiber segments with a pre-terminated connector on one end and a bare fiber on the other. The bare end is mechanically spliced to the incoming fiber, while the connector end plugs into equipment or patch panels. Pigtails are extremely common in single-mode applications and are often used in optical distribution frames (ODFs) and FTTH installations.

They allow for precise, low-loss connections and simplify field termination.

Expanded-

Beam and Multi-Fiber ConnectorsSome mechanical cold splices use expanded-beam connectors or composite ferrules to join multiple fibers simultaneously. Expanded-beam designs reduce sensitivity to dirt and misalignment, making them suitable for rugged or military applications. Multi-fiber mechanical splices allow several fibers to be joined in a single connector, improving installation efficiency in high-density environments.

Summary

The most commonly used fiber optic cold splices include: Mechanical splice connectors (single-fiber, gel-assisted)Splice-on connectors (SOC)Fiber optic pigtailsExpanded-beam and multi-fiber mechanical connectors for specialized applications These cold splicing methods are preferred when fusion splicing is impractical, for temporary repairs, or when field conditions require fast, reliable installation without heat-based equipment.