A first burying layer burying a side of a first ridge structure is formed by selective growth using a first selective growth mask and a third selective growth mask. The first burying layer is formed by regrowth from a surface of a second semiconductor layer on a side of the first ridge structure. At the same time, by selective growth using a second selective growth mask and a fourth selective growth mask, a second burying layer burying a side of a second ridge structure is formed. The second burying layer is formed by regrowth from a surface of a fourth semiconductor layer on a side of the second ridge structure.

A laser device is provided. The laser device includes a bottom plate, a frame body, a heat sink and a light-emitting chip. The light-emitting chip is located on a surface of the heat sink away from the bottom plate. The light-emitting chip includes a plurality of first protrusions and/or a plurality of first depressions, the plurality of first protrusions and/or the plurality of first depressions are located on a first surface of the light-emitting chip; the heat sink includes a plurality of second depressions and/or a plurality of second protrusions, the plurality of second depressions and/or the plurality of second protrusions are located on a second surface of the heat sink; the plurality of first protrusions are located in the plurality of second depressions, and the plurality of second protrusions are located in the plurality of first depressions.

A laser diode apparatus has a first waveguide layer including a gain region connected in series with a second waveguide layer with a second gain region. A tunnel junction is positioned between the first and second guide layers. A single collimator is positioned in an output path of laser beams emitted from the first and second waveguide layers. The optical beam from the single collimator may be coupled into an optical fiber.

A ridge type semiconductor optical device includes a first conductivity type semiconductor layer including at least a first stripe section; an active layer including at least an active stripe section on the first stripe section; a second conductivity type semiconductor layer including at least a second stripe section on the active stripe section; a ridge electrode on the second stripe section; an insulation film on an end face of each of the first stripe section, the active stripe section, and the second stripe section; and a film heater on the insulation film, the film heater overlapping with the end face of at least the first stripe section.

A ridge type semiconductor optical device includes a first conductivity type semiconductor layer including at least a first stripe section; an active layer including at least an active stripe section on the first stripe section; a second conductivity type semiconductor layer including at least a second stripe section on the active stripe section; a ridge electrode on the second stripe section; an insulation film on an end face of each of the first stripe section, the active stripe section, and the second stripe section; and a film heater on the insulation film, the film heater overlapping with the end face of at least the first stripe section.

A Group III-Nitride quantum well laser including a distributed Bragg reflector (DBR). In some embodiments, the DBR includes Scandium. In some embodiments, the DBR includes Al.sub.1-xSc.sub.xN, which may have 0<x≤0.45.

Core-cladding planar waveguide (PWG) structures and methods of making and using same. The core-cladding PWG structures can be synthesized by hydride vapor phase epitaxy and processed by mechanical and chemical-mechanical polishing. An Er doping concentration of [Er] between 1×10.sup.18 atoms/cm.sup.3 and 1×10.sup.22 atoms/cm.sup.3 can be in the core layer. Such PWGs have a core region that can achieve optical confinement between 96% and 99% and above.

A nitride semiconductor laser element includes a stacked structure and a dielectric multilayer film, The dielectric multilayer film includes a first dielectric film, a second dielectric film, and a third dielectric film in the stated order. The nitride semiconductor laser element satisfies the following expressions:

[00001]$.Math.\mathrm{nk}\times \mathrm{dk}+\mathrm{ni}\times \mathrm{di}+\mathrm{nj}\times \mathrm{dj}=m1\times \frac{\lambda }{4}\pm \frac{\lambda }{16};$$\mathrm{nj}\times \mathrm{dj}=m2\times \lambda /4\pm \lambda /16;\mathrm{and}$$\frac{3\lambda }{16}\leqq .Math.\mathrm{nk}\times \mathrm{dk}\leqq \frac{5\lambda }{16}.$

A monolithic edge emitting semiconductor laser comprising multiple laser diodes using aluminum indium gallium arsenide phosphide AlInGaAs/InGaAsP/InP material system, emitting in long wavelengths (1250 nm to 1720 nm). Each laser diode contains an active region comprising aluminium indium gallium arsenide quantum wells (AlInGaAs QW) and aluminum indium gallium arsenide (AlInGaAs) barriers and is connected to the subsequent monolithic laser diode by highly doped, low bandgap and low resistive indium gallium arsenide junction called tunnel junction.

A monolithic edge emitting semiconductor laser comprising multiple laser diodes using aluminum indium gallium arsenide phosphide AlInGaAs/InGaAsP/InP material system, emitting in long wavelengths (1250 nm to 1720 nm). Each laser diode contains an active region comprising aluminium indium gallium arsenide quantum wells (AlInGaAs QW) and aluminum indium gallium arsenide (AlInGaAs) barriers and is connected to the subsequent monolithic laser diode by highly doped, low bandgap and low resistive indium gallium arsenide junction called tunnel junction.