fiber with the core diameter about 8 u03bcm it should be noted in fig5 that almost all the power applied into the optical fiber propagates in the core 8 as the waveguide mode when the beam center of the output beam of the semiconductor laser 6 coincides with the core axis of the optical fiber and then the leakage beam of the cladding mode is minimum further it should be appreciated that the direction of the output beams of a semiconductor laser from a pair of opposite mirror planes coincides completely with each other therefore the axis alignment of the optical fibers is accomplished by positioning the optical fibers by finely adjusting the location in the x and y directions so that the detected signal levels v 1 and v 2 become minimum when the core axes alignment is completed the semiconductor laser 6 in fig4 is removed in the direction r then at least one of the optical fibers 2 and 4 is slid in the z direction which coincides with the core axis direction so that the spacing beteen two optical fibers is appropriate for melting splicing for instance 10 u03bcm then the conventional melting splicing is accomplished by applying an arc to the butt joints the semiconductor laser 6 in the present invention may be either a short wavelength laser or a long wavelength laser further a super luminescence type light emission diode which provides output beams in a pair of opposite directions can be used in the present invention instead of a semiconductor laser further.