Fiber optic cable bundles are composed of individual optical fibers, protective cladding, and outer jacketing materials, with options tailored for specific optical and mechanical requirements.

Core Fiber Materials

The core of each fiber in a bundle is typically made from high-purity silica glass, which can be doped to adjust refractive index for single-mode or multimode operation. Specialized fibers include high-OH silica for UV transmission, low-OH silica for near-infrared (NIR) applications, and ZBLAN (fluorozirconate) fibers for broad UV to mid-IR transmission (285 nm – 4.5 µm) used in spectroscopy and laser applications . Multimode fiber cores range from 25 µm to 1800 µm with numerical apertures (NA) from 0.10 to 0.37 .

Cladding and Protective Layers

Each fiber is surrounded by a cladding layer, usually made of silica with a slightly lower refractive index than the core, which confines light via total internal reflection. Bundles may include epoxy or fused ends to bond fibers, enhancing mechanical stability and high-power handling . For durability, some bundles use stainless steel tubing around fibers, especially in bifurcated or fanout designs .

Outer Jacket Materials

The outer jacket protects the bundle from environmental and mechanical stress. Common materials include PVC, polyurethane, or fluoropolymers, chosen for flexibility, chemical resistance, and temperature tolerance. Custom jackets can be applied for multi-branched or specialized layouts, including round-to-linear or grid configurations .

Bundle Configurations

Fiber bundles can be coherent (maintaining relative fiber positions for imaging) or incoherent (randomized fibers for light transport). Bundles may be configured as spot, line, grid, or hex patterns, with options for combining fibers with electrical wires for integrated applications . The packing fraction (ratio of core area to total bundle cross-section) typically ranges from 50–80%, affecting light collection efficiency .

End Terminations

Bundles are terminated with standard connectors like SMA905 or FC/PC, or with custom ferrules. Connector sleeves may be engraved to indicate fiber type, core size, or NA, ensuring proper identification and alignment . In summary, fiber optic cable bundles are engineered with high-purity silica cores, protective cladding, durable outer jackets, and precise terminations, with material choices tailored to optical wavelength, mechanical flexibility, and application-specific requirements .