valonsäike

Valonsäike is a Finnish term that is commonly used to refer to the optical fiber, a flexible, transparent strand that guides light along its length. It is a central component of modern communication networks and various sensing and imaging systems.

Structure and principle: An optical fiber consists of a core with a higher refractive index surrounded by cladding with a lower refractive index. Light is confined to the core by total internal reflection at the core–cladding boundary. Fibers can be single-mode, carrying light predominantly in one transverse path, or multi-mode, supporting multiple paths. The guiding properties depend on the refractive indices, the wavelength of light, and the fiber’s design, including numerical aperture and dispersion characteristics.

Materials and types: The most common material is silica glass for both core and cladding, while polymer optical fibers use plastic polymers for shorter-range applications. The core may be doped (for example with germanium) to adjust the refractive index. Fiber designs vary to optimize bandwidth, attenuation, and mechanical strength.

Manufacture and performance: Fibers are produced from a preform, often by chemical vapor deposition, and drawn to final diameters. Key performance metrics include attenuation (loss of signal strength), dispersion (pulse broadening), and bandwidth. Modern silica fibers achieve very low losses in the infrared, enabling long-distance transmission and high data rates.

Applications: Valonsäike is used in telecommunications and data networks, medical endoscopy and imaging, fiber-optic sensing (temperature, pressure, strain), and laser delivery. Its development in the 1960s–1970s spurred the adoption of global fiber-optic communication and advanced optical technologies.