Spatial power spectrum characteristics of the core diameter of furnace drawn and laser drawn step-index optical fibers.

Spatial spectral analysis of step-index optical fibers has been performed giving spatial power spectrum data for the core to outer radius ratio, core diameter, and outer diameter variations along the fiber axis. The results show that the geometric cross section existing in the preform is maintained in the fiber even when there are fluctuations in the heat source at 50 Hz or higher. These fluctuations result in periodic fluctuations in the outer diameter and thus the same proportionate fluctuations in the core diameter.