Råfibern

Råfibern, or the bare optical fiber, refers to the glass core and cladding of an optical fiber in its uncoated state, produced directly by the fiber drawing process and before the application of protective polymer coatings. It represents the as-drawn form used in testing, characterization, and preparation for further processing such as splicing and coating.

Bare fiber is extremely delicate and brittle. It is highly sensitive to mechanical stress, moisture, and static electricity, and is typically handled in controlled environments, such as clean rooms or with specialized tooling. After drawing, the fiber is wound onto lightweight reels and inspected for defects. Because it lacks protective coating, råfibern is not suitable for long-term deployment in ordinary conditions and is usually converted into coated fiber for practical use.

Key characteristics include the presence of a microscopic core and cladding structure, with optical properties determined by the core diameter, refractive index profile, and surface quality. The bare fiber must be carefully cleaned and inspected, as surface flaws can impair splicing and connector performance. In practice, råfibern is primarily used by manufacturers and technicians during fusion splicing, coating application, and quality control testing.

Coating and protection are applied promptly after handling, creating a polymer-coated fiber that is robust enough for installation in cables and networks. Safety considerations emphasize the sharp edges of broken or cut glass and the generation of fine fibers or dust, which should be managed with appropriate PPE and disposal procedures.

See also: optical fiber, fiber coating, fusion splicing.