A protective layer, made of glass or plastic, which surrounds the core. The cladding has a lower index of refraction than the core, which helps keep light in the core.是什么意思_A protective layer, made of glass or plastic, which surrounds the core. The cladding has a lower index of refraction than the core, which helps keep light in the core.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句