kuitukaapelia

Fiber optic cable (kuitukaapeli) is a cable containing one or more optical fibers used to transmit information as light. Each fiber has a central core surrounded by a cladding layer with a lower refractive index, enabling guided light by total internal reflection. Fibers are typically made of glass (silica) or plastic and are protected by jackets and strength members.

Types include single-mode fiber, with a small core (about 8–10 micrometers) optimized for long-distance, high-bandwidth links, and multimode fiber, with cores around 50–62.5 micrometers suited to shorter links and lower-cost transceivers. Plastic optical fiber (POF) offers lower cost and easier handling for very short connections.

Construction varies by application. A cable may include one or more fibers with protective jackets (PVC or LSZH). Outdoor or armored designs add water-blocking elements and strength members such as aramid fibers. Common formats include loose-tube and tight-buffer designs. Terminations use connectors (SC, LC, ST, FC) or fusion/mechanical splices.

Transmission and performance: Light is transmitted at near-infrared wavelengths, typically around 850 nm for multimode and 1310–1550 nm for single-mode. Attenuation is usually about 0.2–0.35 dB/km for silicon-based single-mode fibers in the 1310–1550 nm window, with higher losses for multimode. Key metrics include bandwidth–distance products and dispersion, which determine achievable data rates over distance.

Applications: Telecommunications, internet backbones, data centers, campus networks, cable television distribution, and certain medical systems.

Standards: Specifications for fiber types and cabling are governed by ITU-T and IEC/ISO standards, such as ITU-T G.652 for single-mode fiber and related classifications for multimode fibers.