An ICL comprises: a plurality of IC stages, wherein each of the IC stages comprises: a hole injector; an electron injector; an active region coupled to the hole injector and the electron injector and comprising a first layer, wherein the first layer comprises a first material, and wherein the first material comprises InAsP or AlInAsP; a conduction band running through the hole injector, the electron injector, and the active region; and a valence band running through the hole injector, the electron injector, and the active region.

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.

Disclosed is an electrically pumped vertical cavity laser structure operating in the mid-infrared region, which has demonstrated room-temperature continuous wave operation. This structure uses an interband cascade gain region, two distributed mirrors, and a low-loss refractive index waveguide. A preferred embodiment includes at least one wafer bonded GaAs-based mirror.

A quantum cascade laser or interband cascade laser for outputting a frequency comb. The laser's active waveguide comprises a combination of narrow and wide sections which are engineered in combination such that the laser is operable to produce lasing only in the fundamental mode across the operating wavelength range, the narrow section squeezing light propagating in the waveguide to output a frequency comb via four-wave mixing. The narrow and wide sections are further engineered to reduce the waveguide's net GVD, and also to reduce the GVD variation across the operating range compared to a comparable waveguide that is of constant width, thus producing a more stable frequency comb. The proportion of the laser's full dynamic range (i.e. from threshold to the rollover current where the maximum output power is achieved) over which lasing remains in the frequency comb regime is thereby increased compared with a constant width single mode waveguide.

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 laser diode including a double heterostructure comprising a top layer, a buffer layer formed on a substrate, and an intrinsic active layer formed between the top layer and the buffer layer. The top layer and the buffer layer have opposite types of conductivity. The active layer has a bandgap smaller than that of the buffer layer or the top layer. The double heterostructure includes Ge, SiGe, GeSn, and/or SiGeSn materials.

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.

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.

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 laser diode including a double heterostructure comprising a top layer, a buffer layer formed on a substrate, and an intrinsic active layer formed between the top layer and the buffer layer. The top layer and the buffer layer have opposite types of conductivity. The active layer has a bandgap smaller than that of the buffer layer or the top layer. The double heterostructure includes Ge, SiGe, GeSn, and/or SiGeSn materials.