A gain medium for semiconductor optical amplifier in high-power operation includes a substrate with n-type doping; a lower clad layer formed overlying the substrate; a lower optical confinement stack overlying the lower clad layer; an active layer comprising a multi-quantum-well heterostructure with multiple well layers characterized by about 0.8% to 1.2% compressive strain respectively separated by multiple barrier layers characterized by about −0.1% to −0.5% tensile strain. The active layer overlays the lower optical confinement stack. The gain medium further includes an upper optical confinement stack overlying the active layer, the upper optical confinement stack being set thinner than the lower optical confinement stack; an upper clad layer overlying the upper optical confinement stack; and a p-type contact layer overlying the upper clad layer.

A nitride light emitter includes: a nitride semiconductor light-emitting element including an Al.sub.xGa.sub.1-xN substrate (0≤x≤1) and a multilayer structure above the Al.sub.xGa.sub.1-xN substrate; and a submount substrate on which the nitride semiconductor light-emitting element is mounted. The multilayer structure includes a first clad layer of a first conductivity type, a first light guide layer, a quantum-well active layer, a second light guide layer, and a second clad layer of a second conductivity type which are stacked sequentially from the Al.sub.xGa.sub.1-xN substrate. The multilayer structure and submount substrate are opposed to each other. The submount substrate comprises diamond. The nitride semiconductor light-emitting element has a concave warp on a surface closer to the Al.sub.xGa.sub.1-xN substrate.

Provided is a vertical cavity surface emitting laser diode (VCSEL) with low compressive strain DBR layer, including a GaAs substrate, a lower DBR layer, a lower spacer layer, an active region, an upper spacer layer and an upper DBR layer. The lower or the upper DBR layer includes multiple low refractive index layers and multiple high refractive index layers. The lower DBR layer, the lower spacer layer, the upper spacer layer or the upper DBR layer contains Al.sub.xGa.sub.1-xAs.sub.1-yP.sub.y, where the lattice constant of Al.sub.xGa.sub.1-xAs.sub.1-yP.sub.y is greater than that of the GaAs substrate. This can moderately reduce excessive compressive strain due to lattice mismatch or avoid tensile strain during the epitaxial growth, thereby reducing the chance of deformation and bowing of the VCSEL epitaxial wafer or cracking during manufacturing. Additionally, the VCSEL epitaxial layer can be prevented from generating excessive compressive strain or tensile strain during the epitaxial growth.

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 structure includes a semiconductor support, a semiconductor region overlying the semiconductor support, a silicon nitride layer surrounding and straining the semiconductor region, and a metal foot separating the silicon nitride layer from the semiconductor support. The semiconductor region includes germanium. The semiconductor region can be a resonator of a laser or a waveguide.

A broad-spectrum laser for use in a MEMS laser scanning display device is provided. In one example, the broad-spectrum laser includes a laser diode emitter with plural quantum wells each having a different spectral peak. In another example, the broad-spectrum laser includes a laser diode emitter with a tunable absorber to achieve a broadened emissions spectrum. In another example, the broad-spectrum laser includes a laser diode emitter array having plural individual emitters with different spectral peaks.

Disclosed is an optically pumped vertical cavity laser structure operating in the mid-infrared region, which has demonstrated room-temperature continuous wave operation. This structure uses a periodic gain active region with type I quantum wells comprised of InGaAsSb, and barrier/cladding regions which provide strong hole confinement and substantial pump absorption. A preferred embodiment includes at least one wafer bonded GaAs-based mirror. Several preferred embodiments also include means for wavelength tuning of mid-IR VCLs as disclosed, including a MEMS-tuning element. This document also includes systems for optical spectroscopy using the VCL as disclosed, including systems for detection concentrations of industrial and environmentally important gases.

An optical semiconductor device includes a multi-quantum well layer including well layers and barrier layers alternately overlapping with each other, an optical confinement layer, and a guide layer interposed between the multi-quantum well layer and the optical confinement layer. Each barrier layer is an undoped layer and an outermost layer is one of the barrier layers. The optical confinement layer has a refractive index that is greater than that of the outermost layer and a band gap that is smaller than that of the outermost layer. The guide layer includes a first adjacent layer in contact with the outermost layer and the guide layer is thinner than the optical confinement layer. Each of the optical confinement layer and the guide layer is an n-type semiconductor layer. The first adjacent layer of the guide layer has a band gap that is larger than that of the optical confinement layer.

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 broad-spectrum laser for use in a MEMS laser scanning display device is provided. In one example, the broad-spectrum laser includes a laser diode emitter with plural quantum wells each having a different spectral peak. In another example, the broad-spectrum laser includes a laser diode emitter with a tunable absorber to achieve a broadened emissions spectrum. In another example, the broad-spectrum laser includes a laser diode emitter array having plural individual emitters with different spectral peaks.