Patent ID: 7809038

Claim:
A semiconductor optical integrated device comprising: a semiconductor substrate having a top surface and a bottom surface; a semiconductor laser having a signal light wavelength λ signal of 1550 nm at a temperature of 25° C., the semiconductor laser being formed on the top surface of the semiconductor substrate; an electro-absorption optical modulator with a gain peak wavelength λ EA having a quantum well structure, applied with an output light of the semiconductor laser, in which a well layer is made of any one of InGaAlAs, InGaAsP, and InGaAs, and a barrier layer is made of either one of InGaAlAs or InAlAs, the electro-absorption optical modulator being formed on the top surface of the semiconductor substrate; a first electrode formed on the bottom surface of the semiconductor substrate; and a second electrode formed over the top surface of the semiconductor substrate; wherein a difference (E EA −E signal ) between an energy E signal and an energy E EA is 40 meV or more and 70 meV or less, said energy E signal corresponding to the signal light wavelength λ signal of the semiconductor laser at a temperature of 25° C., said energy E EA corresponding to the gain peak wavelength λ EA of the electro-absorption optical modulator at a temperature of 25° C.