Experimental Results on a Single-Material Optical Fiber

The concept of optical fibers made from a single material was the subject of a recent article; 1 the advantages of such fibers are their construction of low-loss fused silica and their freedom from the problems associated with glass interfaces. In this paper, we present experimental results on the dispersion observed in a particular singlematerial fiber. The significance of this work lies in the good agreement between the theory and the experiment; the results do not represent a careful evaluation of single-material fiber as a transmission medium. The results of the experiments are as follows: (i) The predicted modal velocity spread was confirmed. (ii) The measured numerical aperture is directly proportional to wavelength, as predicted by theory. (in) There was very little mode coupling between lowest order modes for lengths up to 100 meters. (iv) Penetration of energy into the support structure was small (the decay constant is about 20 dB//tm).