Determination of optical-fiber diameter from resonances in the elastic scattering spectrum

Highly accurate determination of the outer diameter of unclad glass fibers has been achieved by analyzing, at fixed scattering angle, the wavelength dependence of elastically scattered radiation. The positions of resonance peaks in the scattering spectrum are strongly dependent on fiber diameter. The linewidths of the peaks are sensitive to the circularity of the fiber cross section and to optical loss within or on the fiber surface. This new technique may be useful for the characterization of optical-communication fibers.