摘要 |
PURPOSE:To obtain the low loss light detecting element which is readily manufactured and can divide and detect the waves of wavelength multiplexed light of three or more waves, by sequentially arranging a plurality of light detecting regions having different wavelength sensitivity characteristics from a light incident part, in the order from the light detecting region whose forbidden band width is large to the light detecting region whose forbidden band width is small. CONSTITUTION:A ground potential is applied to an ohmic electrode 8, and a negative potential is applied to ohmic electrodes 9, 10, and 11 through appropriate load resistors. The first light detecting region operates as a light detector for the wavelength region of 1.2mum or less. The second light detecting region 3 operates as a light detector for the wavelength region of 1.35mum or less. The third light detecting region 4 operates as the light detector for the wavelength region of 1.55mum or less. They operate independently. Therefore, when the three wave multiplexed light of wavelengths 1.15mum, 1.3mum, and 1.5mum is inputted into a Zn diffused region 5 at an incident angle of 45 deg. through a light path 101, the light component of the wavelength 1.15mum is detected in the first light detecting region 2. The light components of the remaining wavelengths of 1.3mum and 1.5mum are transmitted through the first detecting region 2 with almost no loss, because an In0.83Ga0.17As0.38P0.62 layer is transparent to the light component of the wavelength of 1.2mum or more. |