A method of forming a laser involves forming, on a substrate, a first epitaxial part of the laser that includes at least an active region layer surrounded by first and second waveguide layers. A dielectric layer is formed over the first epitaxial part. Two or more mask openings are patterned within the dielectric layer. The mask openings extend normal to a light-propagation direction of the laser and are spaced apart in the light-propagation direction of the laser. A second epitaxial part of the laser is formed in the mask openings using selective area epitaxy. The second epitaxial part includes a refractive grating with three-dimensional grating features.

A semiconductor optical device includes a substrate containing silicon and including terraces, a waveguide, and a diffraction grating in different regions in plan view; and a semiconductor device formed of a III-V compound semiconductor and having an optical gain, the semiconductor device being joined to the diffraction grating and the terraces and being in contact with an upper surface of the substrate. The waveguide is optically coupled to the diffraction grating in a direction in which the waveguide extends. The terraces are located on both sides of the waveguide and the diffraction grating in a direction crossing the direction in which the waveguide extends. The substrate has a groove between each of the terraces and the waveguide. The diffraction grating is continuously connected to the terraces in the direction crossing the direction in which the waveguide extends.

A semiconductor optical device includes a substrate including a waveguide made of silicon and a semiconductor layer joined to the substrate so as to overlap the waveguide and including a diffraction grating formed of a first semiconductor layer and a second semiconductor layer having different refractive indices. The waveguide includes a bent portion and a plurality of straight portions that are connected to each other by the bent portion and that extend straight. The first semiconductor layer and the second semiconductor layer are each made of a compound semiconductor. The second semiconductor layer is embedded in the first semiconductor layer and includes a plurality of portions arranged in a direction in which the plurality of straight portions extend. The diffraction grating is positioned above the plurality of straight portions.

A distributed feedback laser (DFB) is a type of laser diode in which the active region of the device contains a periodically structured element or diffraction grating, which may include periodic changes in refractive index that cause reflection back into the laser cavity. Conventional DFB lasers used in optical networks may exploit either loss-modulated or index-modulated gratings. In the case of complex-coupling, index-modulated and loss-modulated gratings may be combined together.

Disclosed is a current-injection organic semiconductor laser diode comprising a pair of electrodes, an optical resonator structure, and one or more organic layers including a light amplification layer composed of an organic semiconductor, which has a sufficient overlap between the distribution of exciton density and the electric field intensity distribution of the resonant optical mode during current injection to emit laser light.

A semiconductor laser accelerator includes several laser acceleration units linked in a cascade manner, and a controller configured to control excitation current supplied to the laser acceleration units. Each laser acceleration unit includes electrodes, an active layer, a first waveguide layer defining one acceleration channel, a second waveguide layer, and a reflecting layer. One or two optical gratings are formed on one or two sides of the acceleration channel to serve as an accelerating area. The semiconductor laser accelerator exhibits a higher acceleration gradient and a smaller structure while not requiring a complex external optical system. In addition, an optical field is controlled by external excitation current, the matching control of an electron beam and an optical field phase can be realized, and the problem of a phase slip can be solved by means of cascade expansion.

The invention relates to a method for fabricating a semiconductor structure. The method comprises fabricating a photonic crystal structure of a first material, in particular a first semiconductor material and selectively removing the first material within a predefined part of the photonic crystal structure. The method further comprises replacing the first material within the predefined part of the photonic crystal structure with one or more second materials by selective epitaxy. The one or more second materials may be in particular semiconductor materials. The invention further relates to devices obtainable by such a method.

A semiconductor optical device includes a substrate including a waveguide made of silicon and a semiconductor layer joined to the substrate so as to overlap the waveguide and including a diffraction grating formed of a first semiconductor layer and a second semiconductor layer having different refractive indices. The waveguide includes a bent portion and a plurality of straight portions that are connected to each other by the bent portion and that extend straight. The first semiconductor layer and the second semiconductor layer are each made of a compound semiconductor. The second semiconductor layer is embedded in the first semiconductor layer and includes a plurality of portions arranged in a direction in which the plurality of straight portions extend. The diffraction grating is positioned above the plurality of straight portions.

Disclosed are a laser structure and a method for fabricating the laser structure. The method includes: providing an epitaxial structure, the epitaxial structure including a substrate, a first doped dielectric layer, a multiple quantum well active layer and a ridge-shaped doped dielectric layer stacked in sequence; forming a grating structure on the ridge-shaped doped dielectric layer and forming a reflective surface on one end of the grating structure, the reflective surface and the grating structure are defined by a same lithography mask, and the mask is protected in a semiconductor etching process selectively, ensuring that relative positions of the reflective surface and the grating structure are not changed, so that light reflected from the reflective surface back to laser cavity has a predetermined phase defined by design, therefore improves performance and stability of the laser, reduces complexity and cost of the fabrication process, and increases yield and reliability.

A method for tuning an emission wavelength of a laser device, including: acquiring a drive condition of a wavelength tunable laser diode to make the wavelength tunable laser diode oscillate at a wavelength from a memory; driving a first thermo-cooler and a first heater based on the drive condition of the wavelength tunable laser diode; determining whether respective control values of the first thermo-cooler and the first heater are reached within a first range of target values; and driving a gain region after the control values have been reached within the first range.