Patent attributes
A semiconductor integrated device includes a plurality of wavelength tunable lasers, provided on a semiconductor substrate, and having oscillation wavelength ranges different from each other. Each of the wavelength tunable lasers includes an optical waveguide including, alternately in an optical axis direction, a gain waveguide portion and a wavelength controlling waveguide portion, and a diffraction grating provided over both the gain waveguide portion and the wavelength controlling waveguide portion. A value obtained by dividing a width of the wavelength controlling waveguide portion by a width of the gain waveguide portion in one of the plurality of wavelength tunable lasers is larger than a value obtained by dividing a width of the wavelength controlling waveguide portion by a width of the gain waveguide portion in a different one of the wavelength tunable lasers, which oscillates on a shorter wavelength side with respect to an oscillation wavelength range of the one wavelength tunable laser.
