This bubble resulted from dirt on the fiber end surface. Proper care should be taken care of during cleaning process of fiber optics by using appropriate cleaning device such as isoprophyl alcohol. It is better to redo the splicing immediately so as to obtain minimum splicing loss. For injection-molded cable products such as optical cables, surface defects are a common product quality problem. However, in real-world installations, whether underground, aerial, or in harsh industrial environments, fiber cables can and do fail. However, physical damage can disrupt this infrastructure and cause significant network issues. They deliver enormous volumes of data through strands of glass thinner than a human hair. This bubble causes extreme fiber optics splicing high loss as shown visually via Visual Fault Locator (VFL) on the right hand side image.
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