Precise axial alignment of fibers to be connected is achieved with a male-to-male arrangement consisting of substantially identical fiber-receiving substrates and a coupler element which takes several configurations. A lensing element such as a ball/sphere is positioned in a well placed directly beyond a precision V-groove formed on a substrate surface, so that the fiber axes extend through substantially the center of the lensing element and are coaxial. The coupler contains a fiber-aligning V-groove and reference surface zones that interact in various ways with two ball-alignment elements of the substrates, to maintain critical substrate surfaces parallel to and precisely spaced from the coupler's reference surfaces.