Abstract: Plural grating couplers having grating conditions different from each other and plural optical waveguides respectively connected with the plural grating couplers are included. The plural grating couplers have the same arraying directions of gratings. Further, each of the plural grating couplers has a different grating interval as a grating condition. Further, plural reflection units respectively provided to the plural optical waveguides are included.

Abstract: A photodiode including a p-type region and an n-type region formed in a core of a grating coupler is provided. The p-type region and the n-type region are each formed as a region having a rectangular shape extending in an array direction of a grating as seen in plan view and are arranged in a direction orthogonal to the array direction of the grating and parallel to a plane of a substrate. A plurality of the p-type regions and a plurality of the n-type regions are formed and alternately arranged.

Abstract: An optical inspection circuit includes an optical circuit to be inspected formed on a substrate, an input optical waveguide optically connected to the optical circuit, and an output optical waveguide optically connected to the optical circuit. The input optical waveguide is connected with a grating coupler for input. The grating coupler is connected with the input optical waveguide via a spot size conversion unit. The output optical waveguide is optically connected with a photodiode.

Abstract: An optical waveguide in which a grating coupler is formed, a first pattern region arranged to surround the grating coupler, and a second pattern region arranged to surround the grating coupler are included. The first pattern region and the second pattern region are arranged adjacently. In a periphery of the grating coupler, the first pattern region is formed in a region continuous in a circumferential direction. Similarly, in the periphery of the grating coupler, the second pattern region is formed in a region continuous in the circumferential direction.

Abstract: The misalignment between light reception lenses and light reception elements in a lens integrated light reception element for converting a plurality of optical signals with different wavelengths into electric signals is easily inspected. The lens integrated light reception element includes one or more light reception lenses that receive the optical signals, one or more light reception elements each disposed on a main axis of the light reception lens and converting the optical signal into the electric signal, one or more inspection pinholes through which illumination light passes, and one or more inspection lenses each including a main axis parallel to the main axis of the light reception lens and converging the illumination light having passed through the inspection pinhole.

Abstract: A light receiving element includes a first substrate, a photodiode formed on a main surface of the first substrate, and a second substrate constituted by a semiconductor and adhered to a rear surface side of the first substrate by an adhesive layer formed from a resin adhesive. A light receiving element according to an embodiment includes a lens that is formed on the side of an adhesion surface of the second substrate, has a convex surface, and is disposed in a light receiving region of the photodiode. The light receiving side of the photodiode is oriented toward the side of the first substrate. The lens is disposed so that the convex surface thereof is oriented toward the side of a light receiving surface of the photodiode.