Optical coupling circuit device

An optical coupling circuit device, comprising:

• an optical circuit board including an optical circuit formed by an optical waveguide;
• an optical fiber coupled to the optical circuit board;
• and
• an optical coupling waveguide that is formed in the optical circuit board and configured to optically couple the optical fiber and the optical circuit, wherein
• the optical fiber includes a cut surface obliquely cut at an angle of 3° or more and 30° or less with respect to an optical axis of the optical fiber, and is coupled to the optical circuit board at the cut surface, and
• with a direction normal to the optical circuit board being defined as a z-direction, a plane orthogonal to the z-direction being defined as an xy-plane, a direction in which an optical axis of the optical coupling waveguide extends toward the optical fiber in the xy-plane being defined as an x-direction, and a direction orthogonal to the x-direction and the z-direction being defined as a y-direction, a second position of a leading end of a core end surface exposed at the cut surface is offset from a first position of a coupling end of the optical coupling waveguide in the x-direction and the z-direction.