Patent ID: 8433164

Claim:
An optical joint comprising: a first multimode interference coupler; and a second multimode interference coupler joined to said first multimode interference coupler, wherein said first multimode interference coupler includes a first port and a second port at one side, and a third port and a fourth port at the other side, said second multimode interference coupler includes a fifth port and a sixth port at one side, and a seventh port and an eighth port at the other side, said third port and said fifth port are joined to each other, said fourth port and said sixth port are joined to each other, a first light-absorbing section is connected to said second port, a second light-absorbing section is connected to said seventh port, and a reflecting boundary that reflects light propagated through said first multimode interference coupler or said second multimode interference coupler is provided to a junction portion between said first multimode interference coupler and said second multimode interference coupler.