The series of passive matching optical fibers manufactured by Yangtze Company, whose core is germanium doped quartz material and optical cladding is high purity quartz material, are made into corresponding passive matching fiber series products through precise geometric design and process control. This series of optical fibers are used to match rare earth-doped active fibers with low fusion loss and good stability of laser output. they are widely used in industrial processing, scientific research, medical treatment, national defense and other fields, and can fully meet the application needs of all kinds of fiber laser users.