▎ 摘　　要

NOVELTY - The light detector (2) has a graphene (12) that is provided with a light receiving region (10) in which a first region (16a) provided with a hole is placed on one end side and a second region (16b) different from the first region is placed on the other end side. A gate electrode (5) faces the light receiving region, and an optical sensor (4) outputs an electric signal in response to light emitted to the light receiving region. A gate voltage applying circuit (6) is provided between light receiving region and gate electrode and is configured for applying gate voltage. The ratio of area of region other than the hole and the area of the first region in the first region is smaller than the ratio of the area of region other than the hole and the area of second region in the second region. The gate voltage is set, so that the ratio of the intensity of electric signal to intensity of the light is set to specific value. USE - Light detector such as graphene photodetector for detecting voltage or graphene light by light irradiation. ADVANTAGE - The graphene light detector can detect light by applying a single voltage to one back gate. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the light detector. Light detector (2) Optical sensor (4) Gate electrode (5) Gate voltage applying circuit (6) Light receiving region (10) Graphene (12) Regions (16a,16b)