enkeltmodusfiber

Enkeltmodusfiber, or single-mode fiber, is an optical fiber designed to transmit light predominantly in a single transverse mode. It features a very small core, typically about 8 to 10 micrometers in diameter, surrounded by a silica cladding of about 125 micrometers and an outer polymer coating. The small core ensures that, at standard telecommunications wavelengths in the near-infrared (roughly 1260 to 1625 nanometers), light propagates mainly as one mode, suppressing higher-order modes.

Because only one mode propagates, modal dispersion is minimized, enabling higher bandwidth over longer distances compared with multimode fibers. Single-mode fiber is usually based on a step-index refractive‑index profile, though certain variants are designed to manage chromatic dispersion for specific systems. Attenuation in modern single-mode fiber is very low in the infrared, especially around 1550 nanometers, making long-haul and submarine links feasible.

Common applications include long-haul telecommunications, metro networks, data centers, and fiber‑to‑the‑premises deployments. The fiber is terminated with adapters and connectors such as LC or SC and is joined by fusion splicing or mechanical splicing. Standards are defined by international bodies such as ITU-T and IEC; widely used specifications describe standard single-mode silica fiber, including its operating wavelengths, dispersion characteristics, and attenuation.

Enkeltmodusfiber is the Swedish term for single-mode fiber, reflecting its defining property of supporting a single guided mode. This characteristic enables high-capacity optical communications over long distances with low signal distortion and loss.