An optical coupling element disposed between an optical fiber and an
optical element that face each other and optically coupling these two
facing components includes a substantially cylindrical optical coupling
portion whose opposite end surfaces respectively face the optical fiber
and the optical element; and a projection projecting radially from a
periphery of the optical coupling portion and being located closer
towards one of the opposite end surfaces with respect to a center
position therebetween. A diameter of the optical coupling portion at a
position corresponding to a first end surface of the projection is
substantially equal to a diameter of the optical coupling portion at a
position corresponding to a second end surface of the projection. The
periphery of the optical coupling portion includes periphery surfaces
tapered from the positions corresponding to the first and second end
surfaces of the projection respectively towards the opposite end
surfaces.