Patent ID: 8170389

Claim:
An optical waveguide comprising a core and a clad, and allowing incident light to be incident thereon, wherein: the core includes a first propagation part, a second propagation part, a third propagation part, and a coupling part that couples the first to third propagation parts together; the first propagation part has a first incidence end face on which part of the incident light is incident, and a first emission part that emits first propagation light, the first propagation light being light that has been incident on the first incidence end face and propagated through the first propagation part; the second propagation part has a second incidence end face on which another part of the incident light is incident, and a second emission part that emits second propagation light, the second propagation light being light that has been incident on the second incidence end face and propagated through the second propagation part; the first propagation part and the second propagation part are spaced apart from each other; the coupling part includes a first incidence part on which the first propagation light emitted from the first emission part is incident, a second incidence part on which the second propagation light emitted from the second emission part is incident, and a third emission part; in the coupling part, a first light wave resulting from the first propagation light incident on the first incidence part and a second light wave resulting from the second propagation light incident on the second incidence part occur, and the first and second light waves interfere with each other to generate third propagation light, the third propagation light being light to be emitted from the third emission part; and the third propagation part has a third incidence part on which the third propagation light emitted from the third emission part is incident, the third propagation part propagating the third propagation light.