The upper surface of the semiconductor substrate has a slope descending from the projection in the second direction at an angle of 0-12° to a horizontal plane. The mesa stripe structure has an inclined surface with a slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55° to the horizontal plane, the mesa stripe structure having an upright surface rising from the inclined surface at an angle of 85-95° to the horizontal plane. The buried layer is made from semiconductor with ruthenium doped therein and is in contact with the inclined surface and the upright surface. The inclined surface is as high as 80% or less of height from the upper surface of the semiconductor substrate to a lower surface of the quantum well layer and is as high as 0.3 μm or more.

A PIC has first, second and third elements fabricated on a common substrate. The first element includes a structure supporting efficient coupling of one or more free-space optical modes of incident light into one or more waveguide guided optical modes. The second element includes an on-chip interferometer having an input optically coupled to the waveguide guided optical modes; one or more arms; one or more outputs; and a phase tuner configured to change optical path length in one or more of the arms. The third element includes one or more light detecting structures optically coupled to the one or more outputs of the second element, such that variation in optical power in the one or more outputs is detected, allowing an assessment of coherence characterizing the light incident on the first element of the PIC to be provided.

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 laser element a first ring resonator. The first ring resonator includes a first semiconductor stack including a first n-side semiconductor layer, a first p-side semiconductor layer, and a first active layer located between the first n-side semiconductor layer and the first A-side semiconductor layer, wherein the first ring resonator comprises a diffraction grating. The semiconductor laser element further includes a second ring resonator optically coupled to the first ring resonator by evanescent field coupling. The second ring resonator includes a second semiconductor stack including a second n-side semiconductor layer, a second p-side semiconductor layer, and a second active layer located between the second n-side semiconductor layer and the second p-side semiconductor layer, wherein a peak wavelength of light emitted by the second ring resonator is the same as a peak wavelength of light emitted by the first ring resonator.

The present invention discloses DFB laser manufacturing method based on dielectric laterally coupled grating with deterministic grating coupling coefficient, comprising: S1: performing photolithography on an epitaxial substrate of the laser without an etch-stop layer to obtain a photoresist pattern with a waveguide morphology in a predetermined geometric configuration, and then performing dry etching and removing the photoresist to obtain a substrate of a waveguide structure in the predetermined geometric configuration; S2: depositing a layer of an insulating film with a low refractive index on the substrate; S3: depositing a dielectric film with a high refractive index on the insulating film; S4: performing photolithography on the dielectric film to prepare a photoresist pattern as a laterally coupled grating morphology; S5: performing etching and removing the photoresist for the dielectric film on the photoresist pattern to prepare a dielectric laterally coupled grating for the laser, and to further prepare a DFB laser.

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.

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.

A QCL may include a substrate, an emitting facet, and semiconductor layers adjacent the substrate and defining an active region. The active region may have a longitudinal axis canted at an oblique angle to the emitting facet of the substrate. The QCL may include an optical grating being adjacent the active region and configured to emit one of a CW laser output or a pulsed laser output through the emitting facet of substrate.

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.

A hybrid distributed feedback (DFB) laser formed from III-V and silicon materials can include a grating in the III-V material to provide optical feedback for mode selection. The grating can include a shift feature in a middle or other parts of the grating to change light output from the gain region. The grating can be a top-surface grating or regrowth can be applied to the III-V structure, which can then be bonded to a silicon structure to couple DFB laser light from the III-V structure to one or more silicon waveguides in the silicon structure.