Method for manufacturing optical interface module and optical interface module

A method for manufacturing an optical interface module, comprising:

• forming a lower clad layer on a flexible substrate;
• forming a core layer on the lower clad layer;
• forming a first core part having one end and an other end, by forming a first set of two grooves in a part of the core layer, the first core part being between the two grooves;
• forming an upper clad layer on the core layer and in the first set of two grooves;
• mounting a light-emitting element on a first rigid substrate;
• mounting a light-receiving element on a second rigid substrate;
• adhering the first rigid substrate and the second rigid substrate to the flexible substrate;
• forming a second core part which is optically coupled to the light-emitting element and to the one end of the first core part respectively by forming a second set of two grooves by laser processing in the upper clad layer and the core layer between the light-emitting element and the one end of the first core part;
• and
• forming a third core part which is optically coupled to the light-receiving element and the other end of the first core part respectively by forming a third set of two grooves by laser processing in the upper clad layer and the core layer between the light-receiving element and the other end of the first core part.

An optical interface module, comprising:

• a substrate;
• a lower clad layer formed on the substrate;
• a three-dimensional core section formed on the lower clad layer and having a first sidewall and a second sidewall opposite to the first sidewall;
• a first resin layer formed on the lower clad layer along the first sidewall of the core section and not touching the first sidewall so as to form a first gap;
• a second resin layer formed on the lower clad layer along the second sidewall of the core section and not touching the second sidewall so as to form a second gap;
• an upper clad layer formed on the core section, on the first resin layer, on the second resin layer, in at least part of the first gap between the core section and the first resin layer, and in at least part of the second gap between the core section and the second resin layer;
• a light-emitting element mounted on the substrate and optically coupled to the core section;
• and
• a light-receiving element mounted on the substrate and optically coupled to the core section, wherein:
• the core section comprises a first core part, a second core part and a third core part, the first core part being between the second and third core parts, and
• a transmission loss in a unit length of the first core part is smaller than a transmission loss in a unit length of the second core part and smaller than a transmission loss in a unit length of the third core part.