Patent ID: 7807954

Claim:
An optical semiconductor module comprising: a light emitting element; a light receiving element that is a mesa-type photodiode and has a light receiving face on an upper face and a side face of a mesa of the light receiving element, with an antireflection film being formed directly on the upper face and the side face; and a mounting unit that has the light emitting element and the light receiving element mounted thereon with such a positional relationship that light emitted from the light emitting element is optically connected at least on the light receiving face of the side face of the light receiving element, wherein: the light receiving element has a light absorption layer, a semiconductor layer of a first conductivity type, and a semiconductor layer of a second conductivity type, the light absorption layer being interposed between the semiconductor layer of the first conductivity type and the semiconductor layer of the second conductivity type; and at least the semiconductor layer of the second conductivity type and the light absorption layer extend on to the side face so that light incident on the light absorption layer through both of the upper face and the side face is converted into electric signal.