Optical fiber product and method of fabricating thereof, Raman amplifier and method of fabricating thereof, method of fabricating of optical coupler, and optical transmission line

摘要

The present invention relates to a fabrication method of an optical fiber product and others capable of effectively restraining increase of loss near the wavelength of 1.38 &mgr;m induced by OH-radical absorption. The fabrication method of the optical fiber product involves the steps of preparing two optical fibers with mutually different mode field diameters, and heating a region near a splice end face of at least one optical fiber with the smaller mode field diameter by a heating source not using a fuel containing pure hydrogen as a constitutive element, before or after a fusion splice is made between these optical fibers. This reduces the OH-radical absorption in the heated region, so as to decrease the increase of transmission loss at the wavelength of 1.38 &mgr;m to 0.1 dB or less.