Determination of monomode fiber buffer properties from bend-loss measurements

Due to a whispering gallery mode, bend loss in monomode optical fibers exhibits oscillations as a function of wavelength. To measure the mean refractive index and thickness of the buffer material on two optical fibers in situ, the period of these oscillations has been used. To an accuracy of + or - 0.0025, which is sufficient to distinguish two nominally identical fibers with buffer surfaces cures of 85% and 96%, the mean refractive index of the buffer material was measured.