ACID STRIPPING OF FUSED-SILICA OPTICAL FIBERS WITHOUT STRENGTH DEGRADATION

Glass optical fibers are almost always coated with a polymer immediate ly after drawing to protect them from subsequent handling damage, When studying the strength and fatigue properties of the fibers, it is use ful to be able to remove this coating in order to directly observe the fatigue properties of the glass in immediate contact with the environ ment. Fused silica optical fibers are frequently stripped by immersion in hut (similar to 200 degrees C) concentrated sulfuric acid. Two rec ent papers have claimed that hot acid stripping significantly degrades the strength and increases the width of the strength distribution, Ho wever, there is a large literature that implies that, at least for mos t coating systems, acid stripping does not degrade the strength provid ed sufficient care is taken to protect the bare fiber surface during s tripping and subsequent testing, This paper explicitly proves this res ult, showing that careful complete stripping has little or no effect o n the strength of fiber tested in both tension and bending, It is also shown that the immersion time in the hot acid has no noticeable effec t on the strength. Experimental protocols are described that minimize the likelihood of accidental damage to the fiber during stripping.