Distributed feedback semiconductor laser and method for producing the same

A semiconductor laser, comprising:

• a striped multiple layer structure comprising a light emission part for emitting laser light and a modulation part which is optically coupled with the emission part for modulating the laser light;
• and
• a semiconductor substrate for supporting the striped multiple layer structure, wherein:
• the emission part comprises an active layer and a plurality of semiconductor regions respectively provided in concave portions of periodical corrugations disposed in a direction of an optical axis so as to be separated from each other, the semiconductor regions being set to have a bandgap energy which is smaller than the energy of light emitted from the active layer, the semiconductor regions being formed of InAsP, each one of the semiconductor regions having a thickness of more than 10 nm, and
• the modulation part comprises a light modulation layer having optical characteristics which change in accordance with a modulation signal.

A semiconductor laser, comprising:

• a striped multiple layer structure comprising a light emission part for emitting laser light and an optical waveguide part which is optically coupled with the light emission part for propagating the laser light therethrough;
• and
• a semiconductor substrate for supporting the striped multiple layer structure, wherein:
• the light emission part comprises an active layer radiating the laser light,
• the optical waveguide part comprises a Bragg reflector where a refractive index periodically changes along an optical axis direction, and the Bragg reflector comprises an InAsP layer formed in concave portions of periodical corrugations formed on the semiconductor substrate so as to reflect light having a selected wavelength of the laser light radiated from the active layer of the light emission part toward the active layer.

A semiconductor laser, comprising:

• a striped multiple layer structure, comprising a light emission part for emitting laser light and a modulation part which is optically coupled with the emission part for modulating the laser light;
• and
• a semiconductor substrate for supporting the striped multiple layer structure, wherein
• the emission part comprises an active layer and a plurality of semiconductor regions respectively provided in concave portions of periodical corrugations disposed in a direction of an optical axis so as to be separated from each other, the semiconductor regions being formed of InAsP and set to have a bandgap energy which is equal to or larger than the energy of light emitted from the active layer, and
• the modulation part comprises a light modulation layer having optical characteristics which change in accordance with a modulation signal.

A semiconductor laser comprising:

• a striped multiple layer structure, comprising a light emission part for emitting laser light and a modulation part which is optically coupled with the emission part for modulating the laser light;
• and
• a semiconductor substrate for supporting the striped multiple layer structure, wherein
• the emission part comprises an active layer,
• the modulation part comprises a light modulation layer having optical characteristics which change in accordance with a modulation signal,
• an absorption type diffraction grating periodically arranged in the optical axis direction, provided in the emission part and the modulation part, and
• the laser light emitted from the active layer is not substantially absorbed at the absorption type diffraction grating in the modulation part.