A folded lasing cavity comprises at least one bend. The folded lasing cavity is disposed on and configured to emit light along a substrate-parallel plane. An etched facet is on an emitting end of the folded lasing cavity and an etched mirror is on another end of the folding lasing cavity. An etched shaping mirror redirects light received from the etched facet in a direction normal to the substrate-parallel plane.

A reflectarray metasurface for quantum-cascade lasing includes: (1) a substrate; and (2) an array of subcavities disposed on the substrate. Each subcavity in the array of subcavities includes (a) a first metallic layer disposed on the substrate; (b) a layer of a quantum-cascade laser active material disposed on the first metallic layer; and (c) a second metallic layer disposed on the layer of the quantum-cascade laser active material. At least some subcavities in the array of subcavities have inhomogeneous widths, and the array of subcavities is configured to reflect an incident light of at least one resonant frequency with amplification.

An optical module includes a circuit board, an optical fiber, an optical fiber monitoring chip, a laser chip, a laser driving chip and a lens assembly. A bottom surface of the lens assembly is covered above the laser chip and the optical monitoring chip. A groove is on a top surface of the lens assembly. A bottom of the groove protrudes to form a first interface and a second interface. The laser chip is configured to emit light. The first interface is configured to reflect the emitted light to obtain first reflected light. The second interface is configured to reflect a portion of the first reflected light to obtain a second reflected light and refract another portion of the first reflected light to obtain a first refracted light. The second reflected light is transmitted to the optical monitoring chip. The first refracted light is transmitted to the optical fiber.

A surface-emitting light source system for generating coherent light having two spin modes comprises a two-dimensional material exhibiting a direct band gap. The two-dimensional material is coupled to a planar heterostructure cavity having an inversion asymmetric core region at least partially surrounded by an inversion symmetric cladding region.

A surface emitting laser includes a semiconductor substrate, a resonance portion that is disposed over the semiconductor substrate and that emits light, an insulating layer disposed in a side face of the resonance portion, and a coating film covering the resonance portion and the insulating layer, wherein a portion disposed in a side face of the insulating layer of the coating film is constituted by an atomic layer deposition film.

An optoelectronic device includes an off-cut III-V semiconductor substrate, a set of epitaxial layers formed on the off-cut III-V semiconductor substrate, and a horizontal cavity surface-emitting laser (HCSEL) having a laser resonant cavity formed in the set of epitaxial layers. The same or another optoelectronic device includes a semiconductor substrate; a laser, epitaxially grown on the semiconductor substrate and having a laser resonant cavity; a semiconductor device, epitaxially grown on the semiconductor substrate and separated from the laser by a single trench having a first vertical wall abutting the laser and a second vertical wall abutting the semiconductor device; and at least one coating on at least one of the first vertical wall or the second vertical wall. The laser resonant cavity of the laser has a horizontal portion parallel to the semiconductor substrate, and each of the first vertical wall and the second vertical wall is oriented perpendicular to the semiconductor substrate.

An optoelectronic device includes an off-cut III-V semiconductor substrate, a set of epitaxial layers formed on the off-cut III-V semiconductor substrate, and a horizontal cavity surface-emitting laser (HCSEL) having a laser resonant cavity formed in the set of epitaxial layers. The same or another optoelectronic device includes a semiconductor substrate; a laser, epitaxially grown on the semiconductor substrate and having a laser resonant cavity; a semiconductor device, epitaxially grown on the semiconductor substrate and separated from the laser by a single trench having a first vertical wall abutting the laser and a second vertical wall abutting the semiconductor device; and at least one coating on at least one of the first vertical wall or the second vertical wall. The laser resonant cavity of the laser has a horizontal portion parallel to the semiconductor substrate, and each of the first vertical wall and the second vertical wall is oriented perpendicular to the semiconductor substrate.

In an embodiment a radiation emitting semiconductor chip includes a semiconductor layer sequence with a plurality of active regions and a main extension plane, wherein each active region has a main extension direction, wherein each active region is configured to emit electromagnetic radiation from an emitter region extending parallel to the main extension plane, wherein at least two active regions overlap in plan view, wherein the emitter regions are arranged at grid points of a regular grid connected by at least one grid line, and wherein the main extension direction of at least one active region encloses an angle of at least 10? and at most 80? with the grid lines of the regular grid.

In an embodiment a radiation emitting semiconductor chip includes a semiconductor layer sequence with a plurality of active regions and a main extension plane, wherein each active region has a main extension direction, wherein each active region is configured to emit electromagnetic radiation from an emitter region extending parallel to the main extension plane, wherein at least two active regions overlap in plan view, wherein the emitter regions are arranged at grid points of a regular grid connected by at least one grid line, and wherein the main extension direction of at least one active region encloses an angle of at least 10? and at most 80? with the grid lines of the regular grid.

A surface-emitting quantum cascade laser of an embodiment comprises a substrate, an active layer, and a photonic crystal layer. The active layer has optical nonlinearity, and is capable of emitting a first and a second infrared laser light. The photonic crystal layer includes a first and a second region. The rectangular grating of the first region is orthogonal to the rectangular grating of the second region. The first infrared laser light has a wavelength corresponding to a maximum gain outside a first photonic bandgap in a direction parallel to a first side of two sides constituting the rectangular grating. The second infrared laser light has a wavelength corresponding to a maximum gain outside a second photonic bandgap in a direction parallel to a second side of the two sides of the rectangular grating.