MANUFACTURE OF TAPERED OPTICAL WAVEGUIDE

摘要

PURPOSE:To manufacture a tapered optical waveguide by one time of heat treatment with good controllability by coating an acid on the surface of a ferroelectric substrate and subjecting the coating to the heat treatment at the temp. different between a light incident part and optical waveguide part. CONSTITUTION:An Al block 3 is heated to 230 deg.C and Al block 4 to 260 deg.C. The LiNbO3 substrate 1 on which pyrophosphoric acid 2 is coated is heat-treated on the blocks 3, 4 so that the tapered optical waveguide is manufactured by a proton exchange. The thickness of the optical waveguide 5 is smaller than the thickness of the light incident part 67 and the waveguide part is thus tapered. A protective mask 7 is formed on the substrate 1 and the above- mentioned stage is executed by which the three-dimensional waveguide to confine light not only in the thickness direction but in the transverse direction as well is obtd. The three parts; the optical waveguide part, tapered part and optical waveguide part are thereby simultaneously manufactured and the process is considerably simplified.