Acid stripping of fused silica optical fibers without strength degradation

Abstract

Glass optical fibers are almost always coated with a polymer immediately after drawing to protect them from subsequent handling damage. When studying the strength and fatigue properties of the fibers, it is useful to be able to remove this coating in order to directly observe the fatigue properties of the glass in immediate contact with the environment. Fused silica optical fibers are frequently stripped by immersion in hot (200 C) concentrated sulfuric acid. Two recent papers have claimed that hot acid stripping significantly degrades the strength and increases the width of the strength distribution. However, there is a large literature that implies that, at least for most coating systems, acid stripping does not degrade the strength provided sufficient care is taken to protect the bare fiber surface during stripping and subsequent testing. This paper explicitly explicitly explicitly proves this result, showing that careful complete stripping has little or no effect on 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 effect on the strength. Experimental protocols are described that minimize the likelihood of accidental damage to the fiber during stripping.

Humidity Dependence of the Fatigue of High‐Strength Fused Silica Optical Fibers

“…Stripping in this way does not degrade the strength of the fiber provided sufficient care is taken both while stripping and during subsequent handling and testing. 23 The fiber strength was measured at five different faceplate velocities (1, 10, 100, 1000, 5000 m/s) using a two-point bending apparatus. 24 The strength was measured in different humidities by allowing the coated fiber to equilibrate overnight in the appropriate environment.…”

Damage of Optical Fibers Under Wet Environments

“…This is the case for very alkaline and fluorinating media [8]. Silica is quite stable in most acids and, as an example immersion into hot sulphuric acid is used for polymer coating stripping [9][10][11][12][13]. While surface flaws may be easily induced on the pristine fiber once the polymer coating is removed, fiber strength is not much affected by this acid etching if fiber is handled properly [10].…”

“…Silica is quite stable in most acids and, as an example immersion into hot sulphuric acid is used for polymer coating stripping [9][10][11][12][13]. While surface flaws may be easily induced on the pristine fiber once the polymer coating is removed, fiber strength is not much affected by this acid etching if fiber is handled properly [10]. On the contrary, fluorinating reagents severely attack silica [14], the intense reaction between silica and hydrofluoric acid being largely used in electronics.…”

Connecting μ-fluidics to electron microscopy

“…These were processed in the following way to optimize the liquid handling and direct the fluid onto the EM grids. The first 0.5--1.0 cm of the polyimide coating of the fused silica capillaries was stripped away using hot chromosulfuric acid (Matthewson et al, 1997). Afterwards, the nozzle was extensively rinsed with ddH20 to remove all traces of the acid.…”