multimode

Multimode is a general term used across science and engineering to describe systems, components, or signals that can operate in more than one mode or state. The precise meaning depends on the field, but it commonly refers to multiple propagation paths, operating conditions, or pattern structures within a single device or signal.

In fiber optics, multimode fiber is a type of optical fiber designed to carry many spatial modes at once. Its larger core diameter (typically 50 or 62.5 micrometers) allows coupling from light-emitting diodes and other inexpensive sources. Because the different modes travel at different speeds, modal dispersion limits the usable distance and bandwidth of multimode links. Multimode fibers are common in short-range applications such as local area networks and data centers, using wavelengths around 850 nanometers or in some cases 1300–1550 nanometers with specialized sources. They contrast with single-mode fiber, which supports only one propagation path and is used for long-distance links.

In lasers and lighting devices, a multimode configuration means the output encompasses several resonant modes. This can yield higher total power but a broader spectral linewidth and less spectral purity. Some systems use multimode operation to balance efficiency, cost, and performance, with mode control implemented through design or active stabilization.

In statistics and signal processing, multimodal (often used as a synonym or closely related concept) describes distributions or signals that exhibit multiple peaks or patterns. Such data are called multimodal and may be analyzed with mixture models or multimodal analysis techniques.

Overall, multimode denotes multiple concurrent modes or patterns within a single system or dataset, with field-specific implications for performance, complexity, and interpretation.