Optical multiplexer/demultiplexer, optical integrated circuit and light transceiver using the same

An optical multiplexer/demultiplexer comprising at least a first core, a second core and a third core arranged in an optical waveguide,

• wherein an end surface of the first core and an end surface of the third core are arranged in opposed relation to each other through the filter in such a manner as to be optically coupled to each other through the filter, the second core is arranged on the same side of the filter as the first core in such a manner as to be optically coupled to the first core through the filter, the first core and the third core each have a curved portion, the curved portion of the first core is formed in a manner protruded toward the second core, the end portion of each of the first and third cores far from the filter reaches a corresponding end of the optical waveguide, and the end portion of the second core far from the filter reaches a side different from the ends of the optical waveguide reached by the first and third cores.

An optical multiplexer/demultiplexer comprising

• at least a first core and a second core arranged in an optical waveguide,
• wherein one end surface of the first core is arranged in opposed relation to a filter, the second core is arranged on the same side of the filter as the first core to be optically coupled to the first core through the filter, and at least a part of the first core is curved in a manner protruded toward the second core, and
• wherein the relation holds that θ>2×θ3, where θ3 is the angle formed between the direction of the optical axis at the end portion of the first core far from the filter and the direction of the optical axis at the end portion of the first core near to the filter, and θ is the angle formed between the direction of the optical axis at the end portion of the first core near to the filter and the direction of the optical axis at the end portion of the second core near to the filter.

An optical multiplexer/demultiplexer comprising at least a first core and a second core arranged in an optical waveguide,

• wherein an end surface of the first core is arranged in opposed relation to a filter, the second core is arranged on the same side of the filter as the first core in such a manner as to be optically coupled to the first core through the filter, and the direction of the optical axis at the end portion of the first core far from the filter is not parallel to an end of the optical waveguide where the end surface of the first core is not located, and
• wherein the end surface of the second core far from the filter is located on a side of the optical waveguide different from the end of the optical waveguide where the end surface of the first core far from the filter is located.

An optical multiplexer/demultiplexer comprising at least a first core, a second core and a third core arranged in an optical waveguide,

• wherein an end surface of the first core and an end surface of the third core are arranged in opposed relation to each other through a filter in such a manner as to be optically coupled to each other through the filter, the second core is arranged on the same side of the filter as the first core in such a manner as to be optically coupled to the first core through the filter, and the direction of the optical axis at the end portion of the first core far from the filter is not parallel to the end of the optical waveguide where the end surface of the first core is not located, and
• wherein the end surface of the second core far from the filter is located at a side of the optical waveguide different from the end of the optical waveguide where the end surfaces of the first and third cores, respectively, far from the filter are located.

An optical multiplexer/demultiplexer comprising at least a first core and a second core arranged in an optical waveguide,

• wherein an end surface of the first core is arranged in opposed relation to a filter, the second core is arranged on the same side of the filter as the first core in such a manner as to be optically coupled to the first core through the filter, and the direction of the optical axis at the end portion of the first core far from the filter is not parallel to an end of the optical waveguide where the end surface of the first core is not located, and
• wherein the relation holds that 0°<θ5<30°, where θ5 is the angle formed between the direction of the optical axis at the end portion of the first core far from the filter and the end of the optical waveguide where the end surface of the first core is not located.