A manufacturing method for an optical semiconductor device includes: forming a first semiconductor layer; forming a first mask pattern on the first semiconductor layer in a first area where an electro absorption type modulator is formed; forming an unevenness along the first direction on the first semiconductor layer; forming a second semiconductor layer on the unevenness; and forming an optical waveguide layer on the second semiconductor layer. The first mask pattern includes a first pattern in the first area and a second pattern in a second area where a DFB laser is formed, the first pattern including a first opening pattern and a first cover pattern, and the second pattern including a second opening pattern and a second cover pattern, and a ratio of the first opening pattern to the first cover pattern is different from that of the second opening pattern to the second cover pattern.

A semiconductor laser device having a diffraction grating is disclosed. The semiconductor laser device comprises a first diffraction grating provided on a substrate, a second diffraction grating continuous to one end of the first diffraction grating along an optical waveguide direction, and an active layer provided above the first diffraction grating. The second diffraction grating has a pitch 1.05 times or greater, or 0.95 times or smaller of the pitch of the first diffraction grating.

In order to prevent non-uniformity in emission wavelength among different sites along an optical axis direction, provided is a resonator portion including: a waveguide which includes a first area and a second area being adjacent to the first area; and diffraction gratings formed along an optical axis direction. The effective refraction index in the first area is larger than the one in the second area, and the thickness in the first area is larger than the one in the second area. A pitch at the adjacent diffraction gratings at a boundary between the first area and the second area is narrower both than pitches of the diffraction gratings that are formed in the first area and than pitches of the diffraction gratings that are formed in the second area.

To provide a semiconductor optical device with device resistance reduced for optical communication. The semiconductor optical device includes an active layer (306) for emitting light through recombination of an electron and a hole; a diffraction grating (309) having a pitch defined in accordance with an output wavelength of the light emitted; a first semiconductor layer (311) including at least Al, made of In and group-V compound, and formed on the diffraction grating; and a second semiconductor layer (307) including Mg, made of In and group-V compound, and formed on the first semiconductor layer (311).

Provided is a butt-jointed (BJ) semiconductor integrated optical device having a high manufacturing yield. A semiconductor integrated optical device, which is configured such that, on a semiconductor substrate, a first semiconductor optical element including an active layer and a second semiconductor optical element including a waveguide layer are butt-jointed to each other with their optical axes being aligned with each other, includes: a semiconductor regrowth layer including at least one of a diffraction grating layer or an etching stop layer, which is formed by one epitaxial growth across an entire surface above the active layer and the waveguide layer; and a cladding layer formed above the semiconductor regrowth layer.

A quantum cascade laser includes a substrate including first and second regions arranged along a first axis; a stacked semiconductor layer disposed in the second region, the stacked semiconductor layer having an end facet located on a boundary between the first and second regions, the stacked semiconductor layer including a core layer and a cladding layer that are exposed at the end facet thereof; and a distributed Bragg reflection structure disposed in the first region, the distributed Bragg reflection structure including a semiconductor wall and a covering semiconductor wall that covers the end facet of the stacked semiconductor layer. The semiconductor wall and the covering semiconductor wall are made of a single semiconductor material. The semiconductor wall has first and second side surfaces. The covering semiconductor wall has an end facet that is located away from the first and second side surfaces of the semiconductor wall.

A laser-diode device includes a substrate; at least one first cladding layer placed on the substrate; an active layer placed on the first cladding layer and arranged to emit a radiation; at least one second cladding layer placed on the active layer, said cladding layers being adapted to form a heterojunction; a first terminal facet and a second terminal facet placed transversally relative to the cladding layers and to the active layer; a periodic structure, placed in proximity to the second terminal facet and within the second cladding layer, and belonging to an optical cavity, wherein the first terminal facet represents the output mirror from which the radiation generated by the active layer exits, and the second terminal facet, integrated by the periodic structure, represents a second mirror having high reflectivity, so that the radiation produced by the active layer exits almost totally through the first mirror.

Disclosed are a current excitation type organic semiconductor laser containing a pair of electrodes, an organic laser active layer and an optical resonator structure between the pair of electrodes and a laser having an organic layer on a distributed feedback grating structure. The lasers include a continuous-wave laser, a quasi-continuous-wave laser and an electrically driven semiconductor laser diode.

Semiconductor device structures comprising laser diode cavities with at least one of a mode-selective filter and a phase-alignment element, and methods for their fabrication, are disclosed. An example device structure comprises a surface-etched grating distributed-feedback (SEG DFB) laser with a mode-selective reflector structure. The reflector structure is designed to provide higher pot feedback of the fundamental TE0 mode and suppression of higher order mode effects. The reflector structure may be a single interface (single facet) mirror type reflector comprising a spatially patterned reflector, or a multi-interface distributed Bragg reflector (DBR). A phase alignment element may be included to provide precise optical phase control. A photodetector for back-facet power monitoring may be included. A method of fabrication is disclosed, based on a self-aligned process in which DBR features are included on the same mask that is used for the DFB laser grating.

A reproducible method for producing a resonant structure of a distributed-feedback semiconductor laser exhibiting a narrow waveguide of the order of some ten micrometers, the production of the diffraction grating being carried out subsequent to the step of producing the strip is provided. In a last step, a diffraction grating is engraved as a function of a desired precise wavelength.