Attenuation measurement in low-loss optical glass by polarized radiation

For the production of fiber waveguides suitable for optical communications cables, glasses with extremelylow attenuation are required. A new method is described for measuring the optical attenuation of bulk glasses in the wavelength range of 0.4-1.1 microm. Using a quartz halogen source with highly stabilized radiation power, a linearly polarized, monochromatic, collimated beam was produced, passing the sample at the Brewster angle. Transmission loss, residual reflection, and surface scattering were measured by low-noise photodiodes and integrating digital voltmeters. A stability of 10(-5) and a resolution of 10(-5) or better were achieved. Results for two different kinds of commercial glasses, fused quartz (Ultrasil) and synthetic vitreous silica (Suprasil W1), are reported and discussed.