An arrayed waveguide, an input-side slab waveguide, an output-side slab waveguide, an input waveguide, and an output waveguide are included. Provided are a groove formed to extend in a direction crossing a plurality of the output waveguides, and an optical conversion unit made of a conversion material that converts near-infrared light to visible light, the groove being filled with the optical conversion unit. The conversion material is, for example, a phosphor or fluorescent substance that converts near-infrared light to visible light.