Transmission loss characteristics of fluorophosphate optical fibers in the ultraviolet to visible wavelength region

Transmission loss properties of fluorophosphate optical fibers were investigated in the 250 to 800 nm wavelength region. The fibers were fabricated by a glass-melting technology in which the core and cladding glasses were prepared by melting the raw materials in vapor atmospheres. The transmission loss of the fiber in the ultraviolet to visible wavelength region is dominated by extrinsic absorptions due to transition metal impurities. The ultraviolet absorption tail is a minor loss factor. The total scattering is the second major loss factor and is in fact Rayleigh having a lambda(-4) dependence, in which the extrinsic scattering loss is due only to waveguide imperfections. This study demonstrates that a stable fluorophosphate glass composition can be prepared using optimized processing technologies, and scattering losses in fibers drawn from this composition can be reduced to these observed in synthetic silica fibers.