A device including a chip including a photonic integrated circuit comprising an external cavity for a source of electromagnetic radiation; the source of electromagnetic radiation attached to a top surface of the chip, the source comprising a semiconductor active region comprising, or coupled to, an output for the electromagnetic radiation, wherein the output is oriented to emit the electromagnetic radiation into the top surface in an emission direction that is inclined with respect to a plane of propagation of the electromagnetic radiation in the external cavity; and a coupler coupling the active region to the external cavity via the top surface to integrate the external cavity with the active region. The coupler partially couples the electromagnetic radiation outputted from the active region to the external cavity, and feedback from the external cavity to the active region.

An optical semiconductor device outputting a predetermined wavelength of laser light includes: a quantum well active layer positioned between a p-type cladding layer and an n-type cladding layer in thickness direction; a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer; and an electric-field-distribution-control layer positioned between the separate confinement heterostructure layer and the n-type cladding layer and configured by at least two semiconductor layers having band gap energy greater than band gap energy of a barrier layer constituting the quantum well active layer.

A broad area semiconductor diode laser device includes a multimode high reflector facet, a partial reflector facet spaced from said multimode high reflector facet, and a flared current injection region extending and widening between the multimode high reflector facet and the partial reflector facet, wherein the ratio of a partial reflector facet width to a high reflector facet width is n:1, where n>1. The broad area semiconductor laser device is a flared laser oscillator waveguide delivering improved beam brightness and beam parameter product over conventional straight waveguide configurations.

An edge-emitting laser having a small vertical emitting angle includes an upper cladding layer, a lower cladding layer and an active region layer sandwiched between the upper and lower cladding layers. By embedding a passive waveguide layer within the lower cladding layer, an extended lower cladding layer is formed between the passive waveguide layer and the active region layer. In addition, the refractive index (referred as n-value) of the passive waveguide layer is larger than the n-value of the extended lower cladding layer. The passive waveguide layer with a larger n-value would guide the light field to extend downward. The extended lower cladding layer can separate the passive waveguide layer and the active region layer and thus expand the near-field distribution of laser light field in the resonant cavity, so as to obtain a smaller vertical emitting angle in the far-field laser light field.

A quantum cascade laser is configured with a semiconductor substrate, and an active layer provided on a first surface of the substrate and having a cascade structure in the form of a multistage lamination of unit laminate structures each of which includes an emission layer and an injection layer. The active layer is configured to be capable of generating first pump light of a frequency .sub.1 and second pump light of a frequency .sub.2 by intersubband emission transitions of electrons, and to generate output light of a difference frequency by difference frequency generation from the first pump light and the second pump light. Grooves respectively formed in a direction intersecting with a resonating direction in a laser cavity structure are provided on a second surface opposite to the first surface of the substrate.

Certain examples described herein relate to a surface-emitting semiconductor-laser which includes an oxide window, a light emitting cavity, and at least one phase matching window. The oxide window, the light emitting cavity, and the at least one phase matching layer are arranged so that a predetermined phase relationship is satisfied. The phase relationship facilitates high performance and stable multimode operations of the surface-emitting semiconductor laser designed to emit between 850-1060 nm wavelength for applications such as long distance optical communications in high performance computing and data servers.

A quantum cascade laser is configured with a semiconductor substrate, and an active layer provided on a first surface of the substrate and having a multistage lamination of unit laminate structures each of which includes an emission layer and an injection layer. The active layer is configured to be capable of generating first pump light of a frequency .sub.1 and second pump light of a frequency .sub.2, and to generate output light of a difference frequency by difference frequency generation. An external diffraction grating is provided constituting an external cavity for generating the first pump light and configured to be capable of changing the frequency .sub.1, outside an element structure portion including the active layer. Grooves respectively formed in a direction intersecting with a resonating direction are provided on a second surface of the substrate.

Certain examples described herein relate to a surface-emitting semiconductor-laser which includes an oxide window, a light emitting cavity, and at least one phase matching window. The oxide window, the light emitting cavity, and the at least one phase matching layer are arranged so that a predetermined phase relationship is satisfied. The phase relationship facilitates high performance and stable multimode operations of the surface-emitting semiconductor laser designed to emit between 850-1060 nm wavelength for applications such as long distance optical communications in high performance computing and data servers.

A semiconductor laser device includes a substrate, a buffer layer provided on an upper surface of the substrate and formed of InP, a laser element having a ridge structure formed above the buffer layer, and an epi intermediate layer formed of a compound semiconductor containing As and exposed to the outside.

A semiconductor laser device includes a semiconductor epitaxial structure, an electrode pad layer, and a transparent conductive layer. The semiconductor epitaxial structure includes a first semiconductor layer, a second semiconductor layer, and a light emitting layer. The light emitting layer is disposed between the first semiconductor layer and the second semiconductor layer, and the first semiconductor layer is disposed between the electrode pad layer and the light emitting layer. The transparent conductive layer is disposed between the electrode pad layer and the first semiconductor layer. The first semiconductor layer has a ridged structure on one side away from the light emitting layer. The electrode pad layer has at least one empty area, and an orthogonal projection of the at least one empty area along a direction perpendicular to the light emitting layer is overlapped with at least a portion of an orthogonal projection of the ridged structure along the direction.