Abstract: An LED optimized for use in low-cost gas or other non-solid substance detection systems, emitting two wavelengths (“colors”) of electromagnetic radiation from the same aperture is disclosed. The LED device emits a light with a wavelength centered on an absorption line of the target detection non-solid substance, and also emits a reference line with a wavelength that is not absorbed by a target non-solid substance, while both wavelengths are transmitted through the atmosphere with low loss. Since the absorption and reference wavelengths are emitted from the same exact aperture, both wavelengths can share the same optical path, reducing the size and cost of the detector while also reducing potential sources of error due to optical path variation.

Abstract: An LED optimized for use in low-cost gas or other non-solid substance detection systems, emitting two wavelengths (“colors”) of electromagnetic radiation from the same aperture is disclosed. The LED device emits a light with a wavelength centered on an absorption line of the target detection non-solid substance, and also emits a reference line with a wavelength that is not absorbed by a target non-solid substance, while both wavelengths are transmitted through the atmosphere with low loss. Since the absorption and reference wavelengths are emitted from the same exact aperture, both wavelengths can share the same optical path, reducing the size and cost of the detector while also reducing potential sources of error due to optical path variation.

Abstract: A method of fabrication of barrier diode based infrared detectors, utilizing the growth of unstrained, not relaxed III-V compound semiconductor material layers having a lattice constant over 6 Angstrom, is provided. The growth is performed by the means of Molecular Beam Epitaxy (MBE) or Metal-Organic Vapor Phase Epitaxy (MOVPE). The method comprises the use of bulk crystalline substrates and the growth of a transitional layer of GaInAsSb with graded composition, followed by an optional thick layer of GaInAsSb of constant composition, lattice matched to the said III-V compound semiconductor material layers, the said optional layer of GaInAsSb of constant composition serving as a virtual substrate. The method provides high crystalline quality layers suitable for semiconductor device fabrication that can effectively interact with electromagnetic radiation of the mid-infrared spectral range with a wavelength between about 2 micrometers to about 16 micrometers.

Abstract: The present invention provides a QCL device with an electrically controlled refractive index through the Stark effect. By changing the electric field in the active area, the energy spacing between the lasing energy levels may be changed and, hence, the effective refractive index in the spectral region near the laser wavelength may be controlled.

Abstract: A method of fabrication of barrier diode based infrared detectors, utilizing the growth of unstrained, not relaxed III-V compound semiconductor material layers having a lattice constant over 6 Angstrom, is provided. The growth is performed by the means of Molecular Beam Epitaxy (MBE) or Metal-Organic Vapor Phase Epitaxy (MOVPE). The method comprises the use of bulk crystalline substrates and the growth of a transitional layer of GaInAsSb with graded composition, followed by an optional thick layer of GaInAsSb of constant composition, lattice matched to the said III-V compound semiconductor material layers, the said optional layer of GaInAsSb of constant composition serving as a virtual substrate. The method provides high crystalline quality layers suitable for semiconductor device fabrication that can effectively interact with electromagnetic radiation of the mid-infrared spectral range with a wavelength between about 2 micrometers to about 16 micrometers.

Abstract: The present invention provides a QCL device with an electrically controlled refractive index through the Stark effect. By changing the electric field in the active area, the energy spacing between the lasing energy levels may be changed and, hence, the effective refractive index in the spectral region near the laser wavelength may be controlled.

Abstract: A semiconductor light source comprises a substrate, lower and upper claddings, a waveguide region with imbedded active area, and electrical contacts to provide voltage necessary for the wavelength tuning. The active region includes single or several heterojunction periods sandwiched between charge accumulation layers. Each of the active region periods comprises higher and lower affinity semiconductor layers with type-II band alignment. The charge carrier accumulation in the charge accumulation layers results in electric field build-up and leads to the formation of generally triangular electron and hole potential wells in the higher and lower affinity layers. Nonequillibrium carriers can be created in the active region by means of electrical injection or optical pumping. The ground state energy in the triangular wells and the radiation wavelength can be tuned by changing the voltage drop across the active region.

Abstract: Computer implemented scheduling systems and associated methods are disclosed. In one embodiment, a method for deriving a roster includes generating a roster within the operational constraint by assigning a plurality of workers to a plurality of individual shifts; calculating a value of the operational outcome based on the assigned shifts in the roster; calculating an overall fatigue value for the assigned individual workers based on the assigned shifts in the roster; and determining whether the generated roster is optimized based on the calculated value of the operational outcome and the overall fatigue value of the workers.

Abstract: Intersubband semiconductor lasers (ISLs) are of great interest for mid-infrared (2-20 ?m) device applications. These semiconductor devices have a wide range of applications from pollution detection and industrial monitoring to military functions. ISLs have generally encountered several problems which include slow intrawell intersubband relaxation times due to the large momentum transfer and small wave-function overlap of the initial and final electron states in interwell transitions. Overall, the ISL's of the prior art are subject to weak intersubband population inversion. The semiconductor device of the present invention provides optimal intersubband population inversion by providing a double quantum well active region in the semiconductor device. This region allows for small momentum transfer in the intersubband electron-phonon resonance with the substantial wave-function overlap characteristic of the intersubband scattering.

Abstract: A semiconductor light source is disclosed comprising a substrate, lower and upper claddings, a waveguide region with imbedded active area, and electrical contacts to provide voltage necessary for the wavelength tuning. The active region includes single or several heterojunction periods sandwiched between charge accumulation layers. Each of the active region periods comprises higher and lower affinity semiconductor layers with type-II band alignment. The charge carrier accumulation in the charge accumulation layers results in electric field build-up and leads to the formation of generally triangular electron and hole potential wells in the higher and lower affinity layers. Nonequillibrium carriers can be created in the active region by means of electrical injection or optical pumping. Radiative recombination occurs between the electrons and holes, accumulated in the ground states of the triangular potential wells formed in the high- and low-affinity layers of each active region periods.

Abstract: Intersubband semiconductor lasers (ISLs) are of great interest for mid-infrared (2-20 ?m) device applications. These semiconductor devices have a wide range of applications from pollution detection and industrial monitoring to military functions. ISLs have generally encountered several problems which include slow intrawell intersubband relaxation times due to the large momentum transfer and small wave-function overlap of the initial and final electron states in interwell transitions. Overall, the ISL's of the prior art are subject to weak intersubband population inversion. The semiconductor device of the present invention provides optimal intersubband population inversion by providing a double quantum well active region in the semiconductor device. This region allows for small momentum transfer in the intersubband electron-phonon resonance with the substantial wave-function overlap characteristic of the intersubband scattering.

Abstract: An apparatus and a method for predicting cognitive performance of an individual based on factors including preferably sleep history and the time of day. The method facilitates the creation of predicted cognitive preformance curves that allow an individual to set his/her sleep times to produce higher levels of cognitive performance. The method also facilitates the reconstruction of past cognitive performance levels based on sleep history.

Abstract: Intersubband semiconductor lasers (ISLs) are of great interest for mid-infrared (2-20 &mgr;m) device applications. These semiconductor devices have a wide range of applications from pollution detection and industrial monitoring to military functions. ISLs have generally encountered several problems which include slow intrawell intersubband relaxation times due to the large momentum transfer and small wave-function overlap of the initial and final electron states in interwell transitions. Overall, the ISL's of the prior art are subject to weak intersubband population inversion. The semiconductor device of the present invention provides optimal intersubband population inversion by providing a double quantum well active region in the semiconductor device. This region allows for small momentum transfer in the intersubband electron-phonon resonance with the substantial wave-function overlap characteristic of the intersubband scattering.

Abstract: A novel InP-based semiconductor laser comprises an unpatterned active region that is essentially co-extensive with the substrate of the laser, an electron stopper layer, and a separate confinement heterostructure (SCH) layer that has a portion of thickness greater than the thickness of the remainder of the SCH layer. The difference in thickness serves to provide lateral guiding of the laser mode. A patterned current blocking layer is disposed on the SCH layer, with a window in the blocking layer defining the region of increased thickness of the SCH layer. The inventive laser is readily manufacturable and can have improved properties.