When light enters a first small diameter fiber at an incident angle of 0°, exit light from the first small diameter fiber has a substantially convex light amount distribution in a diameter direction. When light enters a second small diameter fiber at an incident angle of 12°, exit light from the second small diameter fiber has a substantially concave light amount distribution in a diameter direction. The exit light from the first and second small diameter fibers enters a large diameter fiber and is combined therein, making the light amount distribution uniform in the large diameter fiber. The large diameter fiber has a tapered core and a tapered clad in a light exit section. The light in the large diameter fiber is output from a light exit surface thereof and also leaked from the tapered clad.
