Branch ratio measuring device, branch ratio measuring method, and optical multiplexing/demultiplexing circuit manufacturing method

A branch ratio measuring method comprising:

• a step of setting a polished surface of an active optical fiber core wire and a polished surface of an optical waveguide being put on each other, the active optical fiber core wire having a cladding side-polished to a core or to a vicinity of the core, the optical waveguide having a cladding polished to a core or to a vicinity of the core;
• a step of measuring an optical intensity of an optical signal outgoing from one end of the optical waveguide and an optical intensity of an optical signal reflected on the one end of the optical waveguide and outgoing from the other end of the optical waveguide, the optical signals being included in optical signals that have propagated through the active optical fiber core wire, been demultiplexed by optical coupling, and been partially outgoing from the one end of the optical waveguide, remaining part thereof being reflected;
• and
• a step of calculating a branch ratio from the active optical fiber core wire into the optical waveguide, in accordance with a ratio between the optical intensity of the optical signal outgoing from the one end of the optical waveguide and the optical intensity of the optical signal reflected on the one end of the optical waveguide and outgoing from the other end of the optical waveguide.

An optical multiplexer/demultiplexer circuit manufacturing method comprising:

• a step of setting a polished surface of an active optical fiber core wire and a polished surface of an optical waveguide being put on each other, the active optical fiber core wire having a cladding side-polished to a core or to a vicinity of the core, the optical waveguide having a cladding polished to a core or to a vicinity of the core;
• a step of measuring an optical intensity of an optical signal outgoing from one end of the optical waveguide and an optical intensity of an optical signal reflected on the one end of the optical waveguide and outgoing from the other end of the optical waveguide, the optical signals being included in optical signals that have propagated through the active optical fiber core wire, been demultiplexed by optical coupling, and been partially outgoing from the one end of the optical waveguide, remaining part thereof being reflected;
• a step of calculating a branch ratio from the active optical fiber core wire into the optical waveguide, in accordance with a ratio between the optical intensity of the optical signal outgoing from the one end of the optical waveguide and the optical intensity of the optical signal reflected on the one end of the optical waveguide and outgoing from the other end of the optical waveguide;
• and
• a step of fixing the polished surface of the active optical fiber core wire and the polished surface of the optical waveguide to each other, on condition of the branch ratio calculated as a desired value.