Fiber optic trunk cables are typically spliced using fusion splicing with optical core alignment, often applied to single fibers or entire fiber ribbons at once.

Overview of Fusion Splicing

Fusion splicing is the process of permanently joining two optical fibers by fusing their glass ends using an electric arc, creating a continuous optical path with minimal signal loss and reflection . It is the preferred method for trunk cables because it provides the strongest, most reliable, and lowest-loss connection compared to mechanical splicing .

Splicing Modes for Trunk Cables

1. Single-Fiber Fusion Splicing
   • Each fiber in the trunk cable is spliced individually.
   • Commonly used when fibers are of different types or when precise alignment is critical.
   • Requires a precision cleaver and careful handling to ensure low insertion loss .
2. Ribbon Fusion Splicing
   • Entire fiber ribbons (e.g., 12, 24, or 48 fibers) are spliced simultaneously.
   • Ribbon splicing is highly efficient for trunk cables with multiple fibers, reducing splicing time and ensuring uniform performance across all fibers .

Alignment Techniques

• Optical Core Alignment (Profile Alignment): The most widely used mode for trunk cables. The splicer aligns the fiber cores using optical imaging to ensure precise core-to-core alignment, which is critical for singlemode fibers commonly used in trunk networks .
• Some splicers may also use cladding alignment, but this is less common for high-capacity trunk cables due to slightly higher insertion loss.

Advantages for Trunk Cables

• Low insertion loss (typically ~0.1 dB per splice)
• Minimal back reflection, essential for long-distance singlemode transmission
• High mechanical strength, suitable for buried or aerial trunk installations
• Scalability, especially with ribbon splicing for high-fiber-count cables In summary, fusion splicing with optical core alignment, applied either to individual fibers or entire fiber ribbons, is the standard mode for splicing fiber optic trunk cables due to its reliability, low loss, and efficiency in high-capacity networks .