Patent ID: 11971590
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 3:
4. The method according to claim 2, wherein the optical integrated circuit further comprising:
two more stages of 1×2 branching circuits being connected in series to the 1×2 branching circuit of a first stage in a tree shape; and
corresponding four pairs of waveguides from respective four of the 1×2 branching circuits of a third stage; and
the measuring comprises measuring a sum of photocurrents of an equal number of the waveguides selected respectively from a first waveguide group and a second waveguide group, the four pairs of waveguides having eight waveguides, one branched light from the 1×2 branching circuit on a first stage propagating along the waveguides of the first waveguide group, another branched light from the 1×2 branching circuit on the first stage propagating along the waveguides of the second waveguide group.