Low‐loss single‐ and multimode optical fibers were fabricated solely from pure fused silica. Their spectral losses corresponded closely to those of unclad fibers drawn from the same material, provided the cores of the single‐material fiber preform were redrawn under pure conditions. The lowest steady‐state loss of about 3 dB/km at a wavelength of 1.1 μm was obtained with a fiber 130 meters long that had a Spectrosil WF core. Experimental numerical apertures agreed excellently with theoretical predictions.

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A video-based system, which analyzes the output field of an interference microscope directly, has been developed to measure automatically the refractive-index distribution of optical fibers. Selected regions of the fringe field, detected with a silicon-vidicon, are digitized to 8-bit accuracy by an addressable video digitzer controlled with a programmable calculator. The calculator also makes fringe displacement measurements, corrects for certain misalignments, computes and plots the profile, and determines a best-fit power-law (alpha) curve. Profiles, with relative Deltan measured accurate to a few parts in 10(5), obtained at different wavelengths and for different fiber orientations are presented.

Articles you may be interested inOptical-fiber frequency domain interferometer with nanometer resolution and centimeter measuring range Rev. Sci. Instrum. 84, 113103 (2013); 10.1063/1.4829615Fiber optic multimode displacement sensor AIP Conf.A newly developed technique for directly measuring fiber dispersion in the frequency domain as a function of wavelength is described. A number of germanium· and boron-doped fibers have been examined.The least dispersive borosilicate graded-index fiber has a I-dB bandwidth of I GHz, after 1.07 km of propagation at A = 908 nm. Frequency domain measurements were inverted into the time domain after assuming that the phase of a power transfer function could be calculated from its amplitude spectrum.

An electronic technique to make fringe displacement measurements on the output field of an interference microscope to 1/1000 of a fringe, not including systematic errors, is described. The method, based upon line-selected video signal analysis, is applied to the evaluation of the refractive index profile of a graded index optical fiber. The index difference at a given point between the core and cladding is determined to better than 1 part in 10(5), implying a precision in the profile parameter alpha of +/-0.005, an order of magnitude better than existing techniques.