Fusion splicing is most widely used as it provides for the lowest loss and least reflectance, as well as providing the most reliable joint. Virtually all singlemode splices are fusion. It forms a critical backbone for modern communication networks across both urban and rural environments. Project success depends on careful planning, precise installation practices, and proper. Underground cables are pulled in conduit that is buried underground, usually 1-1. 2 meters (3-4 feet) deep to reduce the likelihood of accidentally being dug up. In extreme cold climates, cables may need to be buried at greater depths where there temperatures are colder and frost penetrates to. Fusion splicing is both an art and a science. The goal is to achieve the lowest possible optical loss (signal. Underground placement is necessary and unavoidable in certain areas for various reasons such as nature and heritage conservation, natural obstacles, aesthetics, space and safety. Placing cables underground has the added benefits of reducing transmission losses, aiding planning consent and reduced. Optical fiber Lengjie is used for optical fiber butt optical fiber or optical fiber docking pigtail, which is equivalent to making a joint, (fiber docking pigtail refers to the butt joint between the optical fiber and the core of the pigtail, not the pigtail head mentioned by the former), used for.