INTEGRATED TYPE BRANCH COUPLER

PROBLEM TO BE SOLVED: To provide an integrated type branch coupler capable of preventing an optical signal from decreasing in signal-to-noise ratio by suppressing unnecessary interference even if radiation light is generated at a branch coupling part.SOLUTION: There is provided an integrated type branch coupler having a substrate 1 and an optical waveguide provided in the substrate right below an upper surface, and the optical waveguide includes one single-mode connection waveguide 2A, a first branch waveguide part comprising a plurality of first single-mode waveguides 2P, 2Q provided on a first side, a first branch coupling part 2R connecting the plurality of first single-mode waveguide to the single-mode connection waveguide, a second branch waveguide part comprising a plurality of second single-mode waveguides 2X, 2Y provided on a second side, a second branch coupling part 2S connecting the second single-mode waveguides to the single-mode connection waveguide, and shield means 17 provided on both sides of the single-mode connection waveguide.