PURPOSE: To provide the optical waveguide of a garnet crystal which is subjected to low-loss connection and has functionability and passive property in combination.
CONSTITUTION: This optical waveguide 1 of the garnet crystal having the functional optical waveguide part 1A and the passive optical waveguide 1B is constituted by using the crystal of the garnet expressed by general formula R3B5O12 (R denotes any one kind among Y, La, Bi and rare earth elements having trivalent valency and B denotes any one kind among Fe, Ga, Al and Sc) or the substitution type garnet in which a part of the constituting elements exclusive of oxygen of garnet are substd. with ≥1 kinds of the elements having the equiv. valency, and by providing a lower clad layer 3 of a garnet crystal film which is nonmagnetic and does not oxhibit fluorescence on a substrate 2, a core part consisting of core layers 5, 7 of the garnet crystals which have prescribed sizes, are aligned in optical axes and have the compsns. varying from each other, on this lower clad layer 3, and an upper clad layer 8 of the garnet crystal which is nonmagnetic and does not exhibit fluorescence on this ore part. Masks consisting of platinum and Ir are used at the time of forming the core layers 5, 7.
SUGIMOTO NAOTO
SHIBUKAWA ATSUSHI