Attention should be paid to the following points: 1 The cone angle of the laser beam should be less than the maximum acceptance angle of the optical fiber, otherwise the total reflection will not be satisfied and the loss will be great. The laser beam should be perpendicular to the fiber end face. 3 fiber end face should be clean. The laser beam is preferably concentric with the end face of the optical fiber. . 5 The laser spot is smaller than the core diameter. The maximum power that optical fiber can bear is greater than laser power. 7 fiber turning radius meets the requirements. Probably the above points. I hope I can help you. I hope to adopt them. Thank you. Laser house laser forum laserhelp answers