Fiber bundles are key components in optical communications and sensing. Their construction method directly impacts the transmission efficiency and reliability of the system. Currently, mainstream construction techniques can be categorized into three types: fused taper, mechanical winding, and resin coupling. Each has its own unique characteristics and is suitable for different scenarios.
The fused taper method involves heating multiple optical fibers at high temperatures to soften and fuse them together, then stretching them to form a tapered coupling structure. This method enables low-loss power distribution or combining (typically <0.5 dB), making it particularly suitable for high-power laser transmission systems. However, the process requires extremely precise temperature control (tolerance <±1°C) and is limited to the construction of silica-based optical fibers.
The mechanical winding method uses precision fixtures to secure the optical fibers in a specific geometric arrangement before packaging. It is commonly used in flexible transmission applications such as medical endoscopes. Its advantages include the lack of high-temperature treatment and compatibility with heterogeneous optical fibers (such as a mixture of plastic and glass fibers). However, over time, coupling efficiency may degrade due to micro-displacement (annual attenuation rate of approximately 0.1-0.3 dB).
The resin coupling process uses UV-curable adhesive to precisely align the fiber end face arrays before curing and forming. It is particularly suitable for the two-dimensional integration of multi-core optical fibers. Recent research shows that the use of gradient index matching adhesive can reduce interface reflection loss to below 0.2dB, but weather resistance issues caused by adhesive aging need to be addressed.
Future development trends focus on breakthroughs in automated assembly technology, such as sub-micron fiber positioning systems based on machine vision and the development of high-temperature-resistant polymer materials. These innovations will promote the large-scale application of optical fiber bundles in harsh environments such as aerospace and quantum communications.
