Optical wavelength converter and method for manufacturing optical wavelength converter

A method for manufacturing an optical wavelength converter comprising:

• a preparation step of preparing a substrate comprised of a crystalline material or an amorphous material, the substrate having a first region and a second region defined to be directly adjacent to each other with a virtual axis therebetween when the substrate is viewed from a reference direction orthogonal to the virtual axis set in the substrate;
• and
• a first processing step of providing in the substrate a plurality of first crystal regions respectively having radial first polarization-ordered structures with radial centers arranged along the virtual axis in the first region of the substrate and a plurality of second crystal regions respectively having radial second polarization-ordered structures with radial centers arranged along the virtual axis in the second region of the substrate, each of the plurality of first crystal regions partially protruding to a second axis across the virtual axis when the substrate is viewed from the reference direction, and each of the plurality of second crystal regions partially protruding to the first region across the virtual axis in a state where the radial centers of the second polarization-ordered structures are arranged alternately with the radial centers of the first polarization-ordered structures when the substrate is viewed from the reference direction, and
• wherein the first processing step comprises a laser light irradiation step, and
• the laser light irradiation step includes irradiating each of a plurality of first condensing points corresponding to the radial centers of the first polarization-ordered structures of the plurality of first crystal regions and each of a plurality of second condensing points corresponding to the radial centers of the second polarization-ordered structures of the plurality of second crystal regions with laser light for formation of the first and second polarization-ordered structures.