A device that includes a metal(III)-polar III-nitride substrate having a first surface opposite a second surface, a tunnel junction formed on one of the first surface or a buffer layer disposed on the first surface, a p-type III-nitride layer formed directly on the tunnel junction, and a number of material layers; a first material layer formed on the p-type III-nitride layer, each subsequent layer disposed on a preceding layer, where one layer from the number of material layers is patterned into a structure, that one layer being a III-nitride layer. Methods for forming the device are also disclosed.

A single-mode micro-laser based on a single whispering gallery mode optical microcavity and a preparation method thereof described includes: preparing a desired single whispering gallery mode optical microcavity doped with rare earth ions or containing a gain material such as quantum dots, wherein an optical microcavity configuration include a micro-disk cavity, a ring-shaped microcavity, and a racetrack-shaped microcavity; a material type include lithium niobate, silicon dioxide, silicon nitride, etc.; preparing an optical fiber cone or an optical waveguide of a required size which can excite high-order modes of the optical microcavity, such as a ridge waveguide and a circular waveguides; and coupling, integrating, and packaging the optical fiber cone or the optical waveguide with the microcavity. A pump light is coupled to the optical fiber cone or the optical waveguide to excite a compound mode with a polygonal configuration.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

A semiconductor optical device includes: a lower mesa structure extending in a stripe shape and composed of some layers including an active layer; a buried layer configured to bury both sides of the lower mesa structure and made of indium phosphide; and an upper mesa structure extending in a stripe shape and composed of some layers including a bottom layer made of phosphorus-free materials, the bottom layer having a bottom surface protruding from a topmost layer of the lower mesa structure, the bottom surface being in contact with the lower mesa structure and the buried layer.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

Semiconductor Quantum Cascade Lasers (QCLs), in particular mid-IR lasers emitting at wavelengths of about 3-50 μm, are often designed as deep etched buried heterostructure QCLs. The buried heterostructure configuration is favored since the high thermal conductivity of the burying layers, usually of InP, and the low losses guarantee devices high power and high performance. However, if such QCLs are designed for and operated at short wavelengths, a severe disadvantage shows up: the high electric field necessary for such operation drives the operating current partly inside the insulating burying layer. This reduces the current injected into the active region and produces thermal losses, thus degrading performance of the QCL. The invention solves this problem by providing, within the burying layers, effectively designed current blocking or quantum barriers of, e.g. AIAs, InAIAs, InGaAs, InGaAsP, or InGaSb, sandwiched between the usual InP or other burying layers, intrinsic or Fe-doped. These quantum barriers reduce the described negative effect greatly and controllably, resulting in a QCL operating effectively also at short wavelengths and/or in high electric fields.

Novel ICL layering designs, ridge waveguide architectures, and processing protocols that will significantly lower the optical losses and improve the power conversion efficiencies of interband cascade lasers designed for both DFB single-mode and high-power applications. The semiconductor top cladding and metal contact layers are eliminated or significantly reduced. By instead using a dielectric or air top clad, or dielectric or air layers to supplement a thin top clad, in conjunction with lateral current injection and weak index-guiding, the present invention will substantially reduce the internal loss of such ICLs, resulting in lower lasing threshold, higher efficiency, and higher maximum power.

A method of manufacturing a semiconductor device includes a step of forming a mesa portion including an active layer above a substrate, and an n-type layer above the active layer, a step of forming a current confinement portion on left and right of the mesa portion, the current confinement portion including a p-type current blocking layer, an n-type current blocking layer above the p-type current blocking layer, and an i-type or p-type current blocking layer above the n-type current blocking layer, and a p-type doping step of diffusing p-type impurities into the i-type or p-type current blocking layer, an upper portion of the n-type current blocking layer, and left and right portions of the n-type layer to change the upper portion of the n-type current blocking layer and the left and right portions of the n-type layer to p-type semiconductors.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

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. The optical semiconductor device includes a separate confinement heterostructure layer positioned between the quantum well active layer and the n-type cladding layer. The optical semiconductor device further includes 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. The optical semiconductor device is applied to a ridge-stripe type laser.