Luminescence originating in an optical fiber

When a pulsed, high-energy, ultraviolet laser beam was coupled into a fused-silica fiber, the fiber was seen to glow a bright red color. The color was intense enough to be seen with the naked eye in a well-lit room, and appeared to be uniform along the length of the fiber. The authors proceeded to study this observed emission. This report summarizes their observations. Experimental data show that removing the fiber optic's cladding, by soaking it in hot, concentrated sulfuric acid, results in elimination of the luminescence phenomenon. Thus, the emission is due either to the cladding or to an interaction between the fused-silica fiber core and the cladding.