| 摘要 |
PROBLEM TO BE SOLVED: To provide a waveguide-type photodetector with a wide dynamic range. SOLUTION: A waveguide-type photodetector is constituted of a photodetection part 15, of a light attenuation part 18 and of a light-transmitting electric isolation part 20 which electrically isolates the photodetection part from the light attenuation part. In the photodetection part, an n-light guide layer 29 and an i-light absorption layer 30 as well as an n-light confinement layer 26 and a p-light confinement layer 32 which sandwich the layers and which form a pair are provided on a substrate 22, and a double heterostructure is formed. The light attenuation part is provided with the same layer structure as the photodetection layer excluding that the light absorption layer is formed of a strained MQW layer, and an electrode 16 for absorption control and an electrode 40 are formed on the upper part and the lower part of the substrate. The light absorption layer and a waveguide at the photodetection layer and the light attenuation part form a ridge structure together with a light confinement structure in the vertical (longitudinal) direction, and they form a confinement structure in the horizontal direction. When a reverse bias voltage is applied to the electrodes at the light attenuation part, the absorption degree of incident light on the light attenuation part is controlled, and the intensity of light which is propagated to the photodetection part can be controlled. |
