Abstract: The amount of light coupled to an optical fiber from a laser diode is limited to a predetermined maximum power. A lens receiving the laser output is adjusted to maximize the power received at the core portion of the fiber endface. The power coupled to the fiber is then reduced to the predetermined power level by insertion of a polarizing or absorbing filter in the optical path. When a polarizing filter is employed, it is rotated until the predetermined power is coupled to the fiber. If a quarter wave plate is included, negative effects due to back reflections from the fiber end face into the laser diode can be eliminated.