An optical fiber is known to bring an optical signal from one fiber end to another fiber end without significant losses. In other cases, the fiber is designed to leak the optical signal in a direction substantially transverse to the propagation direction of the optical signal. This effect is typically the result of the interaction of light (the optical signal) with integrated scattering structures in the fiber or the result of a specific fiber design. The scattering elements may be realized by adding elements such as impurities while drawing the fiber, by processing holes within the fiber, or through mechanical, laser or chemical processing of the fiber.
In still other cases, luminescent materials are integrated inside the fiber-core material, inside the cladding or inside the coating of the fiber to partially or completely convert the propagating wavelength to lower or higher wavelengths.