Optical connection structure and method for manufacturing the same

A method of manufacturing an optical connection structure, the optical connection structure comprising a first optical waveguide, a second optical waveguide having a core diameter different from a core diameter of the first optical waveguide, and a connection optical waveguide disposed between an end surface of the first optical waveguide and an end surface of the second optical waveguide to optically connect the first optical waveguide to the second optical waveguide, the connection optical waveguide including a resin core comprising a photo-curable resin, wherein a core diameter of the resin core gradually changes from a state adapted to the core diameter of the first optical waveguide to a state adapted to the core diameter of the second optical waveguide from a side facing the first optical waveguide to a side facing the second optical waveguide, the method comprising:

• disposing the first optical waveguide and the second optical waveguide such that the end surface of the first optical waveguide and the end surface of the second optical waveguide face each other and are separated by a predetermined interval, wherein the first optical waveguide and the second optical waveguide are secured by a holding member comprising an insertion portion into which the first optical waveguide and the second optical waveguide are inserted, and wherein a spacer comprising a film and disposed at a center of the insertion portion between the end surface of the first optical waveguide and the end surface of the second optical waveguide defines the predetermined interval between the end surface of the first optical waveguide and the end surface of the second optical waveguide;
• after providing the spacer, disposing the photo-curable resin between the end surface of the first optical waveguide and the end surface of the second optical waveguide;
• and
• forming the resin core by guiding a curing light that performs photo-curing of the photo-curable resin through each of the first optical waveguide and the second optical waveguide to perform, with the curing light, the photo-curing of the photo-curable resin disposed between the end surface of the first optical waveguide and the end surface of the second optical waveguide.

A method of providing an optical connection structure, the method comprising:

• providing a first optical waveguide and a second optical waveguide, wherein an end surface of the first optical waveguide is disposed to face an end surface of the second optical waveguide, and wherein the second optical waveguide has a core diameter different from a core diameter of the first optical waveguide;
• providing a holding member for securing the first optical waveguide and the second optical waveguide, wherein the holding member comprises an insertion portion into which the first optical waveguide and the second optical waveguide are inserted;
• providing a spacer comprising a film disposed at a center of the insertion portion between the end surface of the first optical waveguide and the end surface of the second optical waveguide to define an interval between the end surface of the first optical waveguide and the end surface of the second optical waveguide;
• and
• after providing the spacer, disposing a connection optical waveguide between the end surface of the first optical waveguide and the end surface of the second optical waveguide to optically connect the first optical waveguide to the second optical waveguide, the connection optical waveguide including a resin core comprising a photo-curable resin, wherein a core diameter of the resin core gradually changes from a state adapted to the core diameter of the first optical waveguide to a state adapted to the core diameter of the second optical waveguide from a side facing the first optical waveguide to a side facing the second optical waveguide.