OPTICAL WAVEGUIDE ELEMENT, METHOD FOR MANUFACTURING THE SAME AND METHOD FOR FORMING DISTRIBUTION OF REFRACTIVE INDEX

摘要

PROBLEM TO BE SOLVED: To obtain an optical waveguide element having low waveguide loss which can be easily manufactured. SOLUTION: The optical waveguide element is produced by generating the distribution of the refractive index in the core part 2 formed between a substrate 1 as the lower clad and the upper clad part 3 to form a high refractive index region 2a and a low refractive index region 2b so that light is confined and guided in the high refractive index region 2a. The core part 2 is made of a glass material of SiO2 -GeO2 glass having such properties that when the glass is heat treated in the presence of oxygen, the refractive index of the treated region decreases. A specified region of the core part 2 is heat treated in the presence of oxygen to produce the low refractive index region 2b so as to form the high refractive index region 2a and the low refractive index region 2b both having a substantially uniform proportion of cations.