A distributed feedback (DFB) semiconductor laser device includes an active layer, a first grating layer and a second grating. The first grating layer has a first grating structure with a first grating period. The second grating layer has a second grating structure with a second grating period substantially different from the first grating period. The active layer, the first grating layer and the second grating layer are vertically stacked, and the equivalent grating period of the DFB semiconductor laser device is (2P1P2)/(P1+P2), where P1 and P2 respectively represent the first grating period and the second grating period.

A light emitting device includes a unipolar light emitter structured from materials arranged to provide light emission via intersubband transitions of a single type of carrier in either of the conduction band or valence band integrated with a foreign surface.

The invention relates to a distributed feedback laser diode (10) comprising a waveguide with a gain medium assisted by a network formed by a distribution of elements (22) including a sub-set comprising localised resonators (24) distributed along the axis of the waveguide, characterised in that the frequency characteristic of the feedback induced on the wave of the guide by the spatial distribution of said elements differs by less than 50% of the resonance frequency of said localised resonators.

Embodiments provide a light source having a coherent light generator arrangement configured to generate at least one output light, and a waveguide arrangement optically coupled to the coherent light generator arrangement, the waveguide arrangement including at least one first resonator element and at least one second resonator element arranged in different orientations, wherein the waveguide arrangement is configured to interact with the at least one output light to cause the at least one first resonator element and the at least one second resonator element to emit respective first and second optical signals to co-operatively interact with each other to generate an output optical signal, and wherein the light source is configured to change a polarization characteristic of the output optical signal in response to at least one electrical signal applied to the light source to vary at least one of respective magnitudes of the first and second optical signals relative to each other.

The invention relates to a III-V heterostructure laser device (1) arranged in and/or on silicon, comprising: a III-V heterostructure gain medium (3); and an optical rib waveguide (11), arranged facing the gain medium (3) and comprising a slab waveguide (15) equipped with a longitudinal rib (17), the optical rib waveguide (11) being arranged in the silicon. The optical rib waveguide (11) is oriented so that at least one Bragg grating (19, 19a, 19b) is arranged on that side (21) of the slab waveguide (15) which is proximal relative to the gain medium (3) and in that the rib (17) is placed on that side (23) of the slab waveguide (15) that is distal relative to the gain medium (3).

A semiconductor laser includes a first optical waveguide including a first reflection unit and a second reflection unit, and a confinement portion. The first reflection unit and the second reflection unit are waveguide type reflection units each having a structure in which the refractive index is periodically modulated. The first reflection unit, the confinement portion, and the second reflection unit constitute a Fabry-Perot type optical resonator. The semiconductor laser also includes a second optical waveguide disposed along a first optical waveguide to extend from the confinement portion to the second reflection unit side. The second optical waveguide serves as an extraction optical waveguide. Further, a third reflection unit formed continuously with the second optical waveguide is provided at a location corresponding to the first reflection unit.

A photonic device comprising: a support; an intermediate layer comprising at least one dielectric material and a first and second excess thickness of silicon separated from each other by a space; a first patterned silicon layer at least partially forming a waveguide, and first to fifth waveguide sections; a first dielectric layer covering the first silicon layer and a gain structure comprising at least one gain medium in contact with the first dielectric layer; the second and fourth wave guide sections, the first and second excess thicknesses of silicon, and the first and second ends of the gain structure forming a first and second optical transition zone between a hybrid laser waveguide, formed by a central portion of the gain structure, the space and the third waveguide section and the first and fifth waveguide sections respectively. The invention also relates to a method of fabricating such a photonic device.

A quantum cascade laser includes: a substrate having a principal surface, a back surface, and a substrate end face, the substrate end face extending along a reference plane intersecting a second direction which intersects the first direction; a semiconductor laminate having a laminate end face extending along the reference plane; a first electrode disposed on the semiconductor laminate; a second electrode disposed on the substrate; a first insulating film disposed on the laminate end face and the first electrode; a metal film disposed on the first insulating film, the laminate end face, the substrate end face, and the second electrode; and a second insulating film disposed on the first electrode, the second insulating film having a part on the first electrode between the metal film and the semiconductor laminate. On the first electrode, the second insulating film has a thickness larger than that of the first insulating film.

A quantum cascade laser includes: a semiconductor device portion having a substrate, a semiconductor laminate, and a semiconductor insulating portion, the semiconductor laminate having a principal surface, the substrate having a back surface and a substrate end face, the semiconductor laminate having a laminate end face, the semiconductor insulating portion and the substrate being arranged along a reference plane intersecting the second direction, the semiconductor device portion having a front end face and a rear end face, the front end face and the rear end face being arranged in the second direction, the rear end face including the substrate end face, and the substrate end face extending along the reference plane; a first electrode disposed on the semiconductor laminate; and a metal film disposed on the rear end face, the semiconductor insulating portion and the second electrode, the metal film being apart from the first electrode.

A grating device includes an optical material layer; a channel type optical waveguide region provided in the optical material layer; extension regions provided on the outsides of the channel type optical waveguide region, respectively; a Bragg grating provided in the channel type optical waveguide region; and periodic microstructures provided in the extension regions, respectively. The periodic microstructures are provided in 50 percent or larger of a total of areas of the extension regions.