Abstract: An optical receptacle includes a first optical surface, a second optical surface, and an annular first cylindrical part disposed to surround a second central axis of the second optical surface. The first cylindrical part includes a first inner surface with a circular shape in a cross section perpendicular to the second central axis, and a second inner surface disposed on a second optical surface side than the first inner surface and provided with a circular shape in the cross section perpendicular to the second central axis. A diameter of the first inner surface is greater than a diameter of the second inner surface, and a length of the second inner surface in a direction along the second central axis is 0.5 to 4.0 mm.

Abstract: An optical receptacle includes: a first optical surface configured to allow, to enter the optical receptacle, light emitted from the photoelectric conversion element package, or emit, toward the photoelectric conversion element package, light travelled inside the optical receptacle; a second optical surface configured to emit, toward the optical transmission member, the light travelled inside the optical receptacle, or allow, to enter the optical receptacle, light emitted from the optical transmission member; a cylindrical part configured to house at least a part of the photoelectric conversion element package such that the first optical surface and the photoelectric conversion element face each other; and a first groove part disposed at a periphery of the first optical surface.

Abstract: An optical receptacle includes an optical receptacle main body and a cylindrical fixing member. The optical receptacle main body includes a first optical surface, a second optical surface, and an annular groove disposed to surround a first central axis of the first optical surface or disposed to surround a second central axis of the second optical surface. The fixing member is configured with a material with a smaller linear expansion coefficient than that of the optical receptacle main body, and is fit to the groove so as to be in contact with at least a part of an inner surface of the groove.