Fusion splicing mode of trunk optical cables

Trunk optical cables are typically fusion spliced using fixed (hot) fusion mode with precise core alignment to ensure low-loss, high-reliability connections.Fusion Splicing Modes for Trunk Cables1. Fixed (Hot) Fusion Splicing: This is the standard method for trunk optical cables, where the fiber ends are melted together using a high-voltage electric arc. The fibers are gently pushed together by a precision motion mechanism to achieve mode field coupling, resulting in a permanent, low-loss joint. This method is preferred for mainline or backbone networks due to its high signal quality, minimal reflection, and long-term reliability . 2. Temporary (Cold) Connection: Involves inserting fibers into connectors without melting. While convenient and low-cost, this method has higher insertion loss and lower mechanical strength, making it unsuitable for trunk cables where performance and durability are critical . 3. Active Connection: Uses fiber connecting devices to join fibers flexibly. It allows easy reconfiguration but introduces higher loss and reflection, so it is rarely used for permanent trunk installations .Alignment Techniques1. Optical Core Alignment (Profile Alignment): Many trunk fusion splicers use profile alignment, where the fiber cores are illuminated from multiple directions and captured by cameras. Software then aligns the cores automatically using movable stages, ensuring optimal light transmission and minimal splice loss . 2. LID Core Alignment (Local Injection and Detection): Light is injected into one fiber and detected in the other, with the splicer adjusting fiber positions to maximize transmission. This method is effective for both single fibers and ribbon fibers in trunk cables .Operational ConsiderationsFiber Preparation: Strip the outer jacket and coating carefully, clean with 99%+ isopropyl alcohol, and cleave precisely using a high-quality cleaver to avoid microfractures .Splice Protection: After fusion, a heat-shrink sleeve is applied to protect the splice from moisture and mechanical stress .Ribbon vs Single-Fiber Splicing: Trunk cables often contain ribbon fibers, which can be spliced simultaneously using ribbon fusion splicers to improve efficiency and maintain uniform loss across multiple fibers .Environmental Factors: Trunk splicing may occur in harsh conditions; modern splicers like the Komshine FX39 are designed for high-altitude, dry, or cold environments, maintaining consistent fusion quality .SummaryFor trunk optical cables, hot fusion splicing with precise core alignment is the recommended mode. It ensures low-loss, durable, and reliable connections suitable for backbone networks. Proper fiber preparation, alignment, and splice protection are critical to achieving optimal performance. Temporary or active connections are generally reserved for testing or short-term setups due to higher loss and lower mechanical strength.