Wavelength conversion element and method for manufacturing wavelength conversion element

A method of fabricating a wavelength conversion device that includes a plurality of waveguides formed on a substrate of a nonlinear material and a plurality of slab waveguides that are arranged substantially in parallel with and spaced apart from the plurality of waveguides, the method comprising:

• a step of fabricating a guided light attenuator formed of a material having an index of refraction different from an index of refraction of a material forming the slab waveguides in the plurality of slab waveguides;
• a step of successively measuring an optical characteristic of the plurality of waveguides and selecting one waveguide having a desired optical characteristic from the plurality of waveguides;
• and
• a step of increasing at least the index of refraction of the material forming the guided light attenuator that is formed in the slab waveguide that is located on one side of the selected waveguide and adjacent to the selected waveguide.

A wavelength conversion device, comprising:

• a plurality of waveguides formed on a substrate of a nonlinear material;
• a plurality of slab waveguides that are arranged substantially in parallel with and spaced apart from the plurality of waveguides;
• and
• guided light attenuators formed of a material having an index of refraction different from an index of refraction of a material forming the slab waveguide in the plurality of slab waveguides,
• wherein the guided light attenuator is a groove formed in the slab waveguide as an internal region thereof by removing the material forming the slab waveguide, and of slab waveguides adjacent to one of the plurality of waveguides, at least the groove formed in the slab waveguide on one side of the one waveguide is filled with a material having an index of refraction greater than 1, and
• wherein on a face of the substrate, the guided light attenuator has a shape that is asymmetrical with respect to a light guide direction in the plurality of slab waveguides.