These structures include sleeves for fixing optical fibers, pins for precise alignment of optical fibers, and sealing rings for ensuring sealing performance. Fiber adapters, also known as fiber optic couplers or fiber optic connectors, are essential components in fiber optic networks that enable the connection of two fiber optic cables or devices., two fiber connectors) such that light can reliably pass from one to the other with minimal insertion loss and maximum return loss. A fiber optic adapter, also known as a fiber coupler, is a passive device used to connect and align two optical fiber connectors. The sleeve is usually made of ceramic material with extremely high hardness and smoothness to reduce friction and loss when the optical fiber.