What does fiber optic fusion splicing mode mean

Fusion splicing typically uses optical core alignment (also called profile alignment) to precisely align fiber cores before fusing.

Overview of Fusion Splicing

Fusion splicing is the process of permanently joining two optical fibers end-to-end by melting their glass ends together, usually with an electric arc, to create a low-loss, low-reflection, and mechanically strong joint . It is the preferred method for single-mode fibers due to their small core size and sensitivity to misalignment, though it is also used for multimode fibers.

Alignment Techniques

The mode used in fusion splicing refers to the method of aligning the fiber cores before fusing:

• Optical Core Alignment (Profile Alignment): This is the most common method in modern fusion splicers. The splicer uses cameras and image processing to detect the fiber cores and align them precisely. This ensures minimal splice loss and back reflection, which is critical for single-mode fibers .
• Cladding Alignment: Some splicers, especially for multimode fibers, align the fibers based on the outer cladding rather than the core. This method is simpler but less precise for single-mode fibers, where core alignment is essential.

Process Summary

1. Fiber Preparation: Protective coatings and jackets are stripped, leaving the bare fiber.
2. Cleaving: Fibers are cleaved with a precision cleaver to create flat, perpendicular ends.
3. Alignment: The splicer automatically aligns the fibers using optical core alignment or cladding alignment.
4. Fusion: An electric arc melts the fiber ends, fusing them together.
5. Protection: The splice is protected with a heat-shrink sleeve or similar protector.

Applications

• Single-mode fibers: Optical core alignment is almost always used due to the small core diameter (~9 µm) and the need for extremely low splice loss.
• Multimode fibers: Cladding alignment may be sufficient, though optical core alignment can still be used for higher precision. In summary, optical core alignment is the primary mode used for fiber optic fusion splicing, ensuring precise core-to-core alignment and optimal performance, especially for single-mode fibers .