Abstract: A semiconductor optical device 1 includes an active layer 4 provided on a substrate 2, a clad layer 5 provided on the active layer 4, and a contact layer 7 provided on the clad layer 5. The contact layer 7 contains a first impurity and a second impurity different from the first impurity. A semiconductor light source includes the active layer 4 provided on the substrate 2, the clad layer 5 provided on the active layer 4, and the contact layer 7 provided on the clad layer 5. The contact layer 7 contains the first impurity and the second impurity different from the first impurity.

Abstract: There is provided a photoelectric converter that converts an optical signal into an electrical signal for amplification, the photoelectric converter including a photoelectric conversion element that converts the optical signal into an electrical signal and outputs the electrical signal from an output terminal, a high-frequency amplifier that includes an input terminal of an electrical signal output from the output terminal and a DC cut-off capacitor which is disposed at an output stage of the input terminal and is serially connected to the input terminal and that amplifies the electrical signal, and an inductance element that is disposed between a bias power supply applying bias voltage or bias current to the photoelectric conversion element and the input terminal and which is connected in parallel to the DC cut-off capacitor.

Abstract: A semiconductor optical device 1 includes an active layer 4 provided on a substrate 2, a clad layer 5 provided on the active layer 4, and a contact layer 7 provided on the clad layer 5. The contact layer 7 contains a first impurity and a second impurity different from the first impurity. A semiconductor light source includes the active layer 4 provided on the substrate 2, the clad layer 5 provided on the active layer 4, and the contact layer 7 provided on the clad layer 5. The contact layer 7 contains the first impurity and the second impurity different from the first impurity.