Optical fuse by carbon-coated TeO2 glass segment inserted in silica glass optical fiber circuit

Excessive-light-induced melt down was observed in a carbon-coated TeO2 glass segment formed between a pair of optical fiber end-faces. This structure was made by splicing single-mode silica fibers through TeO2 glass melt to form a necked bridge, which was coated with carbon-containing paint after quenching it. Optical fusing action was induced by 0.3--1.5 W of CW light (1.54 um) and its output power dropped by 12 dB on average. Optical decoupling seems to be induced by not only deformation but also crystallization of the glass bridge. Its quite a high insertion loss of about 2dB can be reduced by introducing some refractive index modulations into the present structure.