Optical fuse made of silica glass optical fibers spliced through low-melting glass with carbon-coating

Light-induced breakdown of low-melting glass with thickness of 50 um is demonstrated, which was coated with carbon paint and formed between two end of single-mode silica glass optical fibers. This phenomenon is useful to make irreversible optical limiting devices known as optical fuse. The present structure breaks by 1.2-5.3 W of incident light (~1.5 um), exhibits low insertion loss of less than 1 dB, and is formed by dipping-up a small amount of hot glass melt between fibers, aligning the fibers and quenching them. The relation between shape of the captured melt and its insertion loss is discussed.