SELECTIVE MODIFICATION OF INSIDE OF SOLID MATERIAL AND SOLID MATERIAL WITH SELECTIVELY MODIFIED INSIDE

摘要

PROBLEM TO BE SOLVED: To provide a material for an optical element in which such a region is formed in the inside that refractive index is changed in a prescribed pattern. SOLUTION: A light-gathering point is controlled in a specific region and pulse laser is convergently irradiated to a solid material having such a plurality of regions in the inside that rare earth ions and/or transition metallic ions are contained and refractive indexes are mutually different. Valance number of the rare earth ions and/or transition metallic ions in the specific region is selectively changed. Such regions are selectively formed in the material irradiated with laser that valence number of rare earth ions and/or transition metallic ions is changed by convergent irradiation of pulse laser in the inside of the specific region. Refractive index of the region in which the valence number of ions is changed, differs from the other region.