An optical module includes at least one optical fiber, a gradient index rod lens,
and an optical element. The rod lens is placed at a position separated from an
end surface of the optical fiber by a space. The optical element is separated from
the rod lens. Outgoing light from the single optical fiber is inputted to the optical
element via the rod lens, and light reflected by the optical element is coupled
to the optical fiber via the rod lens. When a distance between the rod lens and
the optical element is longer than a predetermined value, and a lens length optimized
for the distance is equal to or less than a predetermined pitch, the rod lens has
end surfaces perpendicular to an optical axis.