Preparation and an optical member of the optical member, the optical member forming the transparent member, an optical waveguide and an optical module

The present invention provides an optical waveguide manufacturing method and low light loss of the optical member that can control the refractive index of the surface layer portion and in the vicinity of the center of the core pattern of the transparent member positionally accurate. The optical member manufacturing method of the present invention, a transparent member exposed to the solution, the refractive index of the surface layer portion of the transparent member which is exposed to a solution, substantially from the refractive index of the central portion of the transparent member which is not exposed to solution a step a to lower. Substantial low refractive streamlining of the surface layer portion can be achieved by expressing its function in the refractive index control agent to be contained in the surface layer portion of the transparent member. Further, the optical waveguide of the present invention mainly comprises a surface portion around the two or more sides of the core pattern forming the core portion has a lower refractive index than the central portion of the core pattern, said surface layer portion is low wherein the refractive index control agent for the refractive index, further to the outer surface region having a low refractive index, has a more lower cladding layer and / or upper cladding layer of low refractive index.