Separation of total-loss data into its absorption and scattering components: a more accurate model for fiber loss

A technique is presented that uses total-loss data from a conventional monochromator-based spectral-loss measurement set to obtain not only the Rayleigh and wavelength-independent scattering of a fiber but also the UV-band-edge absorption. That absorption causes the total-loss data to deviate significantly from a straight line when the data are plotted vs lambda on a 1/lambda(4) scale. Including the absorption term accounts for the deviation from a straight line over an extended wavelength region (0.66-1.16 microm) and materially affects the A and B coefficients obtained. For one fiber examined in detail A went from 1.30 to 1.13 microm(4) dB/km and B from 0.22 to 0.32 dB/km when the UV absorption was included. This technique also eliminates the problem of negative B coefficients and allows processing variables that affect absorption to be separated from those that affect scattering.