ARTICLE CONTAINING OPTICAL ELEMENT AND MANUFACTURE THEREOF

PURPOSE: To provide an optical element provided with an area locally substantially turned to a high refractive index. CONSTITUTION: By a processing for exposing at least a part of glass to H2 or D2 (the partial pressure of H2 or D2 is more than 1 atmospheric pressure) at the temperature of 250 deg.C or less and irradiating at least a part of an exposed part with the radiation 34 having chemical activity (UV in a typical case), unpredictably large standardized refractive index change (Δ>10 ), probably larger than 10-3) is obtained in oxide glass like high silica glass for instance. This method is used for the manufacture of the optical element including the area (or plural areas) of the high refractive index like an in-line refractive index in an optical waveguide, a planer optical waveguide or a phase diffraction grating, for instance.