OPTICAL WAVEGUIDE AND ITS PRODUCTION

摘要

PURPOSE:To manufacture an optical waveguide having an optional refractive index value and optional refractive index distribution by an extermely simple method by using an oxynitride film consisting of silicon oxide and nitrogen oxide as a part of a core or a clad. CONSTITUTION:The refractive index of the oxynitride film constituted of a mixed film of silicon oxide and a nitrogen oxide is suddenly reduced by guiding a small quantity of O2 gas. Therefore, the oxynitride film having an optional refractive index between the refractive index of SiO2 glass and that of an Si3N4 film can be formed by selecting the ratio of N2 to O2 in sputtering atmosphere. The sputtering condition of the oxynitride film is that the mixed gas of O2 and N2 having partial pressure allowing the refractive index of the obtained oxynitride film to be set up to a required value is used as the sputtering gas. Thus, the optical waveguide can be simply manufactured only by changing the composition of gas at the sputtering time in accordance with time passage even if its refractive index distribution has any value.