Abstract: A noninvasive mid-infrared in vivo glucose sensor for use in connection with the skin of a test subject is disclosed. The sensor includes a mid-infrared light source configured to deliver a light beam to the skin of the test subject, a collector element configured to collect backscattered light from the skin and direct it to the detector, and a detector element configured to measure the collected backscattered light from the skin. The mid-infrared light source may be a quantum cascade laser. The sensor may include optical fibers configured to deliver the light beam to the skin of the test subject. The collector element may be an integrating sphere or a bundle of two or more optical fibers. The sensor may also include a probe containing or connecting to optical fibers coupled to the mid-infrared light source and configured to be placed on the skin to take glucose level readings.

Abstract: In one aspect, semiconductor lasers are provided. A semiconductor laser described herein comprises substrate and a cavity formed on the substrate, the cavity comprising an asymmetric Mach-Zehnder (AMZ) interferometer structure positioned between two straight waveguide segments, the straight waveguide segments and first and second arms of the AMZ interferometer structure comprising epitaxial semiconductor layers, wherein the second arm of the AMZ interferometer structure has a temperature control architecture independent of the first arm.

Abstract: In one aspect, semiconductor lasers are provided. A semiconductor laser described herein comprises substrate and a cavity formed on the substrate, the cavity comprising an asymmetric Mach-Zehnder (AMZ) interferometer structure positioned between two straight waveguide segments, the straight waveguide segments and first and second arms of the AMZ interferometer structure comprising epitaxial semiconductor layers, wherein the second arm of the AMZ interferometer structure has a temperature control architecture independent of the first arm.

Abstract: A noninvasive mid-infrared in vivo glucose sensor for use in connection with the skin of a test subject is disclosed. The sensor includes a mid-infrared light source configured to deliver a light beam to the skin of the test subject, a collector element configured to collect backscattered light from the skin and direct it to the detector, and a detector element configured to measure the collected backscattered light from the skin. The mid-infrared light source may be a quantum cascade laser. The sensor may include optical fibers configured to deliver the light beam to the skin of the test subject. The collector element may be an integrating sphere or a bundle of two or more optical fibers. The sensor may also include a probe containing or connecting to optical fibers coupled to the mid-infrared light source and configured to be placed on the skin to take glucose level readings.

Abstract: The present invention relates generally to highly power-efficient quantum cascade sources, such as highly power-efficient quantum cascade lasers having ultra-strong coupling between injector and active regions which may be configured to provide broadband quantum cascade lasers.

Abstract: The present invention relates generally to highly power-efficient quantum cascade sources, such as highly power-efficient quantum cascade lasers having ultra-strong coupling between injector and active regions which may be configured to provide broadband quantum cascade lasers.

Abstract: A quantum cascade source, such as a QC laser, is provided comprising a plurality of repeat units each including an active region and an injector region. The active region includes at least two quantum wells that, in response to an applied electrical bias, provide a first, second, and third electron energy level, each resulting from a respective quantum well excited state. The first and second energy levels are configured so that an electron transition from the first energy level to the second energy level emits a photon of a selected wavelength. The second and third energy levels are configured so that an electron transition from the second energy level to the third energy level comprises a nonradiative transition to empty the second energy level sufficiently quickly to promote a population inversion between the first and second energy levels.

Abstract: An optoelectronic transducer comprises a unipolar, intraband active region and a micro-cavity resonator. The resonator includes a 2D array of essentially equally spaced regions that exhibits resonant modes. Each of the spaced regions has a depth that extends through the active region and has an average refractive index that is different from that of the active region. The refractive index contrast, the spacing of the spaced regions, and the dimensions of the spaced regions are mutually adapted so that the array acts as a micro-cavity resonator and so that at least one frequency of the resonant modes of the array falls within the spectrum of an optoelectronic parameter of the active region (i.e., the gain spectrum where the transducer is a laser; the absorption spectrum where the transducer is a photodetector). In a first embodiment, the transducer is an ISB laser, whereas in a second embodiment it is a unipolar, intraband photodetector.

Abstract: A broadband CLE capable of operation simultaneously at multiple wavelengths comprises: a core region including a multiplicity or cascade of stages, each stage including a radiative transition region. A first group of stages emits radiation at a first wavelength and at a first aggregate intensity per group, and a second group of stages emits radiation at a second wavelength and at a second aggregate intensity per group lower than the first intensity. The invention is characterized in that the second group has more stages than said first group, and the per-stage intensity of the first group is greater than that of the second group. This design reduces the difference between said first and second aggregate intensities. In one embodiment, groups that are located at or near to the ends of the cascade have more stages than groups that are centrally located within the cascade regardless of their wavelength.

Abstract: An optical device comprises a cavity resonator and an intracavity ridge waveguide. The ridge waveguide includes a monolithically integrated intersubband core region and a nonlinear mixing region (NMR). In response to external pumping energy the core region generates laser light at a first frequency and in a first transverse mode. In response to the laser light the NMR generates parametric light at a second frequency and in a second transverse mode. For phase matching the effective-refractive-index-versus-ridge-width characteristics of the modes of the laser and the parametric light intersect one another at a phase matching width and so that, at greater widths, the effective refractive index of the mode of the higher frequency light is less than that of the lower frequency light. For true phase matching the width of the ridge is made to be essentially equal to the phase matching width.

Abstract: A quantum well structure is provided that includes two or more quantum well layers coupled by at least one barrier layer such that at least one of a piezo-electric field and a pyro-electric field is produced. The quantum well structure is sufficiently doped to cause a Fermi energy to be located between ground states and excited states of the coupled quantum well layers. The quantum well structure can be incorporated into a layered semiconductor to form optical devices such as a laser or optical amplifier.

Abstract: A compact optical resonator that exhibits long TOPLs is fabricated by (a) selecting a 3-dimensional (3D) reflective, essentially closed surface such that the paths of optical rays that reflect from the interior of the surface include chaotic, open paths; (b) determining the phase-space of the reflection points of the rays; (c) within the phase-space identifying at least one forbidden zone where there are no such reflection points and at least one allowed zone where there is a multiplicity of such reflection points; (d) forming the surface inside a rigid body; and (e) forming at least one physical feature that communicates with the interior of the resonator and is located in a region of the surface that is determined by the positions of the forbidden zones, the allowed zones, or both. In a preferred embodiment physical features such as gas ports are located in regions of the surface that, in phase space, correspond to forbidden zones (so that the circulating optical rays cannot escape via the gas ports).

Abstract: Techniques for amplifying light produced by a quantum cascade laser are described. An assembly according to the present invention includes an optical amplifier having an optical input and an optical output. The optical output has an area significantly greater than that of the optical output and the geometry of the amplifier is such that the amplifier widens from the optical input to the optical output. The optical amplifier is formed of a layered waveguide structure which achieves quantum confinement of electrons and photons within the active region. A distributed feedback laser is suitably coupled to the optical amplifier at the optical input of the amplifier. The widening of the amplifier makes available a large number of electrons, so that the amplifier is able to produce many photons resulting from stimulated transitions caused by introduction of light to the optical input of the amplifier, even if the great majority of the transitions occur nonradiatively.

Abstract: A monolithic apparatus has a laser optical cavity. The laser optical cavity has a multi-layer structure that includes a first active semiconductor multi-layer and a second semiconductor multi-layer. The second semiconductor multi-layer is located laterally adjacent to the first active semiconductor multi-layer. The first active semiconductor multi-layer includes a sequence of quantum well structures that produce light of a lasing frequency in response to being electrically pumped. The second semiconductor multi-layer includes a sequence of quantum well structures and is configured to both absorb light of the lasing frequency and produce one of parametric light and harmonic light in response to absorbing light of the lasing frequency.

Abstract: A compact optical resonator that exhibits long TOPLs is fabricated by (a) selecting a 3-dimensional (3D) reflective, essentially closed surface such that the paths of optical rays that reflect from the interior of the surface include chaotic, open paths; (b) determining the phase-space of the reflection points of the rays; (c) within the phase-space identifying at least one forbidden zone where there are no such reflection points and at least one allowed zone where there is a multiplicity of such reflection points ; (d) forming the surface inside a rigid body; and (e) forming at least one physical feature that communicates with the interior of the resonator and is located in a region of the surface that is determined by the positions of the forbidden zones, the allowed zones, or both. In a preferred embodiment physical features such as gas ports are located in regions of the surface that, in phase space, correspond to forbidden zones (so that the circulating optical rays cannot escape via the gas ports).

Abstract: The measurement of intersubband electroluminescence (ISB-EL) in unipolar quantum cascade lasers is achieved by forming a longitudinal cleave through the active region and waveguide of the QC laser device, exposing a complete side face of the device, including the active region. The conventional laser facets at the entrance and exit of the active region are coated with a highly reflective material and the emission from the exposed side face is measured. In theory, the sideface emission would comprise only the ISB-EL spontaneous emission, but some additional laser emission (due to scattering in the imperfect waveguide structure) also exits along this sideface. Spatial filtering and/or polarization monitoring can be used to differentiate the laser emission from the ISB-EL spontaneous emission.

Abstract: In an intersubband light emitter, at least two injection/relaxation (I/R) regions contiguous with the same RT region have different doping levels. Preferably, one I/R region has a doping level that is at least 100 times lower than that of the other I/R region. In one embodiment, one I/R region is undoped, whereas the other I/R region is doped.

Abstract: An optical device includes a stack of at least two different intersubband (ISB) optical sub-devices in which the gain/loss profiles of the individual ISB sub-devices are mutually adapted, or engineered, so as to generate a predetermined overall function for the combination. We define this combination device as being heterogeneous since not all of the individual ISB sub-devices are identical to one another. Illustratively, the parameters of each individual ISB sub-device that might be subject to this engineering process include: the peak energy of the ISB optical transitions (emission or absorption) associated with each RT region, the position of each sub-device in the stack; the oscillator strengths of these ISB transitions; the energy bandwidth of each transition; and the total length of the RT and I/R regions of each ISB sub-device.

Abstract: A monolithic apparatus has a laser optical cavity. The laser optical cavity has a multi-layer structure that includes a first active semiconductor multi-layer and a second semiconductor multi-layer. The second semiconductor multi-layer is located laterally adjacent to the first active semiconductor multi-layer. The first active semiconductor multi-layer includes a sequence of quantum well structures that produce light of a lasing frequency in response to being electrically pumped. The second semiconductor multi-layer includes a sequence of quantum well structures and is configured to both absorb light of the lasing frequency and produce one of parametric light and harmonic light in response to absorbing light of the lasing frequency.

Abstract: Techniques for amplifying light produced by a quantum cascade laser are described. An assembly according to the present invention includes an optical amplifier having an optical input and an optical output. The optical output has an area significantly greater than that of the optical output and the geometry of the amplifier is such that the amplifier widens from the optical input to the optical output. The optical amplifier is formed of a layered waveguide structure which achieves quantum confinement of electrons and photons within the active region. A distributed feedback laser is suitably coupled to the optical amplifier at the optical input of the amplifier. The widening of the amplifier makes available a large number of electrons, so that the amplifier is able to produce many photons resulting from stimulated transitions caused by introduction of light to the optical input of the amplifier, even if the great majority of the transitions occur nonradiatively.