fiber coupler adapter is a detachably (movable) connection device between fiber and fiber. It is to precisely butt two end faces of fiber, so that the optical energy output of the transmitting fiber can be coupled to the receiving fiber to the maximum extent, and make its intervention in the optical link to minimize the impact on the system. A waveguideOptical fiber coupler adapter is generally a device with a Y-shaped branch in which the optical signal input by one fiber can be divided into equal parts. When the open Angle of the branch of the Optical fiber coupler adapter increases, the light leakage to the cladding will increase to increase the excess loss, so the open Angle is generally within 30°, so the length of the waveguide fiber coupler can not be too short.