Classification of Optical Fiber Cables by Primary Structure

Various types of optical cables have been designed to meet specific application requirements and environmental conditions. While their structural forms are diverse, they can generally be categorized as follows:

1. Tight-structured optical cables: In this structure, the optical fibers are twisted into a cable at specific pitches and tightly embedded in plastic. Stranded optical cables may use either tight-buffered or loose-buffered fibers. In loose-buffered fibers, because the fibers have a certain amount of slack within the plastic sheath, they have some room to move when the cable is stretched, thereby reducing the strain on the fibers relative to the strain on the cable itself.

2. Loose-tube optical cables: In this structure, the optical fibers occupy a larger space and have relative freedom of movement. This cable structure not only possesses good tensile strength but also excellent impact resistance, with minimal micro-bend attenuation caused by cabling. Its disadvantage is that the manufacturing process is relatively complex.

3. Ribbon-structured optical cables: This is a specialized cable structure in which multiple optical fibers are arranged in rows to form ribbon-like cable units, which are then twisted together in a specific pattern to form the cable. This type of cable is characterized by high space efficiency, ease of fiber handling and identification, and the ability to splice multiple fibers simultaneously. The drawbacks include a complex manufacturing process, as well as difficulties in controlling micro-bend attenuation caused by processing and the cable’s temperature characteristics.