A gallium and nitrogen containing laser diode device. The device has a gallium and nitrogen containing substrate material comprising a surface region. The surface region is configured on either a non-polar crystal orientation or a semi-polar crystal orientation. The device has a recessed region formed within a second region of the substrate material, the second region being between a first region and a third region. The recessed region is configured to block a plurality of defects from migrating from the first region to the third region. The device has an epitaxially formed gallium and nitrogen containing region formed overlying the third region. The epitaxially formed gallium and nitrogen containing region is substantially free from defects migrating from the first region and an active region formed overlying the third region.

A method of producing a plurality of laser diodes includes providing a plurality of laser bars in a compound, wherein the laser bars each include a plurality of laser diode elements arranged side by side, the laser diode elements each have a common substrate and a semiconductor layer sequence arranged on the substrate, and a splitting of the compound at a longitudinal separation line running between two adjacent laser bars in each case leads to formation of laser facets of the laser diodes to be produced, and structuring the compound at at least one longitudinal separation line, wherein a strained compensation layer is applied to the semiconductor layer sequence at least at the longitudinal separation line or the semiconductor layer sequence is at least partially removed.

An optical device has a gallium and nitrogen containing substrate including a surface region and a strain control region, the strain control region being configured to maintain a quantum well region within a predetermined strain state. The device also has a plurality of quantum well regions overlying the strain control region.

A quantum cascade laser including: a laser structure having a first region including a first facet, a second region including a second facet, an epitaxial surface, and a substrate surface; an insulating film disposed on the second facet and the epitaxial surface; an electrode disposed on the epitaxial surface and the insulating film and in contact with the epitaxial surface; and a metal film disposed over the second facet and the epitaxial surface and separated from the electrode and the substrate surface. The insulating film is disposed between the metal film and the second facet and between the metal film and the epitaxial surface. The second region includes a semiconductor mesa. The second facet is located at a boundary between the first region and the second region. The first region includes a connecting surface. The connecting surface connects the second facet to the first facet.

A quantum dot comb laser includes a body defining a lasing cavity and an extension defining an external cavity, the FSR of the lasing cavity being an inverse of an integer multiple of the FSR of the external cavity.

A semiconductor optical amplifier includes a conductive region that is provided on a substrate and allows light transmission, and a nonconductive region that is provided around the conductive region and prohibits light transmission. The conductive region includes a first region including a light-coupling portion to which light from an external light-source unit is coupled, and a second region having a narrower width than the first region and connected to the first region through a connecting portion, the second region including a light-amplifying portion amplifying the light from the light-coupling portion by propagating the light in a predetermined propagating direction along a surface of the substrate, the light-amplifying portion outputting the amplified light in a direction intersecting the surface of the substrate. Seen in a direction perpendicular to the surface of the substrate, the semiconductor optical amplifier includes a portion where a width of the conductive region is continuously reduced from the first region to the second region.

A gallium- and nitrogen-containing laser device including a facet with surface treatment to improve an optical beam is disclosed.

In some implementations, a laser diode array may comprise a cavity that includes a rear facet and a front facet and multiple emitters that are transversely single mode and disposed within the cavity. In some implementations, the multiple emitters each include a seeding section having a constant emitter width that is single mode at the rear facet and a flared section having a monotonically expanding emitter width that increases adiabatically over a majority of a length of the cavity such that outputs from the multiple emitters are single mode at the front facet. In some implementations, the emitter width is less than twenty micrometers at the front facet.

A QCL may include a substrate, and a semiconductor layer adjacent the substrate. The semiconductor layer may define branch active regions, and a stem region coupled to output ends of the branch active regions. Each branch active region may have a number of stages less than 30.

A QCL may include a substrate, and a semiconductor layer adjacent the substrate. The semiconductor layer may define branch active regions, and a stem region coupled to output ends of the branch active regions. Each branch active region may have a number of stages less than 30.