Optical scanning element

An optical scanning element, comprising:

• a photonic crystal layer having holes periodically formed in an electro-optical crystal substrate;
• a line-defect optical waveguide formed in the photonic crystal layer;
• a diffraction grating arranged in at least one portion selected from an upper portion, a left side surface portion, and a right side surface portion of the line-defect optical waveguide;
• electrodes arranged on a left side and a right side of the line-defect optical waveguide;
• a support substrate arranged below the electro-optical crystal substrate, the support substrate being configured to support the electro-optical crystal substrate;
• a joining portion configured to integrate the electro-optical crystal substrate and the support substrate with each other;
• a cavity defined by a lower surface of the electro-optical crystal substrate, an upper surface of the support substrate, and the joining portion;
• and
• a clad layer arranged on an upper surface of the photonic crystal layer,
• the optical scanning element being configured so that an emission angle of light emitted from an upper surface of the line-defect optical waveguide is changed,
• wherein the diffraction grating is arranged in a portion on an upper surface of the clad layer corresponding to the line-defect optical waveguide, wherein the diffraction grating has a plurality of grating grooves extending in a direction substantially perpendicular to a waveguide direction of the line-defect optical waveguide,
• wherein the line-defect optical waveguide has a length of 5 mm or less,
• wherein the electro-optical crystal substrate includes one selected from the group consisting of:
• lithium niobate;
• lithium tantalate;
• potassium titanate phosphate;
• potassium lithium niobate;
• potassium niobate;
• potassium tantalate niobate;
• and a solid solution of lithium niobate and lithium tantalate,
• wherein the electrodes are transparent to light, and are arranged above the photonic crystal layer so as to overlap the holes.