PRODUCTION OF OPTICAL WAVEGUIDE

PROBLEM TO BE SOLVED: To make productivity high, cost low and loss low and to make it possible to arbitrarily control the refractive index difference between core and clad by forming the cores and upper clad layer by a screen printing method or spin coating method. SOLUTION: This optical waveguide has a lower clad layer 3 on a substrate 2 and the cores 4 having a rectangular section on the lower clad layer 3. Both flanks and front surfaces of the cores 4 are coated with the upper clad layer 5. The formation of the cores 4 and the upper clad layer 5 is executed by applying a coating liquid contg. glass power by screen printing or spin coating, then, baking the coating. The screen printing method or spin coating method is used for forming the lower clad layer 3 in the case the optical waveguide having the structure having the lower clad layer 3 on the substrate 2 is manufactured. A method for applying the coating liquid contg. the glass powder by the screen printing or spin coating, then baking the coating is used for the formation of the cores 4 and the clad layer 3.