A coherent light source includes a plurality of light emitting points arranged in one-dimensional array. A beam shaping unit shapes a light beam so that a diameter of a light emitted from the coherent light source in a direction perpendicular to a direction of the light emitting point array is larger than a diameter in the direction of the light emitting point array, and an intensity distribution of the light emitted from each of the light emitting points is uniform. A magnification of a focusing optical system is set such that a light emitted from the beam shaping unit is coupled to an optical fiber based on a maximum diameter of the light emitted from the beam shaping unit.