(JP9064399-A)      The waveguide type photodetector (10) of a wide dynamic range, comprises a detector section (14), an attenuator section (18) and a transparent separator section (20) for electrically isolating the detector section and the attenuator section. The detector section includes an n-type light guide layer (28) and an i-type light absorption layer (30), and paired n- and p-type layers (26 and 32) for optical confinement sandwiching the layers (238 and 30) on a substrate (22), so as to form a double-hereto-structure.    The attenuation section has the same layer structure as the detector section with the exception that the light absorption layer is formed by a strained MQW layer, and an electrode (16) for absorption control and an electrode (40) are disposed on the front and back surface of the substrate. The detector section, the light absorption layer of the attenuator section and the waveguide constitute a ridge structure with the optical confinement structure in a vertical direction, and form the confinement structure in the horizontal direction. A reverse bias voltage is applied to the electrodes of the attenuator section to control the degree of absorption of incident light to the attenuator section so that the intensity of light propagated to the detector section may be controlled.    USE/ADVANTAGE -   E..g. for optical CATV systems.    (US5926585-A)      The waveguide type photodetector (10) of a wide dynamic range, comprises a detector section (14), an attenuator section (18) and a transparent separator section (20) for electrically isolating the detector section and the attenuator section. The detector section includes an n-type light guide layer (28) and an i-type light absorption layer (30), and paired n- and p-type layers (26 and 32) for optical confinement sandwiching the layers (238 and 30) on a substrate (22), so as to form a double-hereto-structure.    The attenuation section has the same layer structure as the detector section with the exception that the light absorption layer is formed by a strained MQW layer, and an electrode (16) for absorption control and an electrode (40) are disposed on the front and back surface of the substrate. The detector section, the light absorption layer of the attenuator section and the waveguide constitute a ridge structure with the optical confinement structure in a vertical direction, and form the confinement structure in the horizontal direction. A reverse bias voltage is applied to the electrodes of the attenuator section to control the degree of absorption of incident light to the attenuator section so that the intensity of light propagated to the detector section may be controlled.    USE/ADVANTAGE -   E..g. for optical CATV systems.    (CN1164933-A)      The waveguide type photodetector (10) of a wide dynamic range, comprises a detector section (14), an attenuator section (18) and a transparent separator section (20) for electrically isolating the detector section and the attenuator section. The detector section includes an n-type light guide layer (28) and an i-type light absorption layer (30), and paired n- and p-type layers (26 and 32) for optical confinement sandwiching the layers (238 and 30) on a substrate (22), so as to form a double-hereto-structure.    The attenuation section has the same layer structure as the detector section with the exception that the light absorption layer is formed by a strained MQW layer, and an electrode (16) for absorption control and an electrode (40) are disposed on the front and back surface of the substrate. The detector section, the light absorption layer of the attenuator section and the waveguide constitute a ridge structure with the optical confinement structure in a vertical direction, and form the confinement structure in the horizontal direction. A reverse bias voltage is applied to the electrodes of the attenuator section to control the degree of absorption of incident light to the attenuator section so that the intensity of light propagated to the detector section may be controlled.    USE/ADVANTAGE -   E..g. for optical CATV systems.