Abstract: Structures and methods for reducing the thermal resistance of quantum cascade laser (QCL) devices and QCL-based photonic integrated circuits (QCL-PIC) are provided, wherein, in various embodiments, the native substrate of QCL and QCL-PIC devices is replaced with a foreign substrate that has very high thermal conductivity, for example, using wafer bonding methods. In some examples, wafer bonding of processed, semi-processed, or unprocessed QCL and QCL-PIC epilayers or devices on their native substrate to a high-thermal-conductivity substrate is performed, followed by removal of the native substrate via selective etching, and performing additional device processing if necessary. Thereafter, in some embodiments, cleaving or dicing individual devices from the bonded wafers may be performed, for example, for mounting onto heat sinks.

Abstract: An optical construction includes a lens layer and optically opaque first and second mask layers. The lens layer has a first major surface including a plurality of microlenses arranged along orthogonal first and second directions. The first and second mask layers are spaced apart from the first major surface and define respective pluralities of through first and second openings therein arranged along the first and second directions. The first mask layer is disposed between the structured first major surface and the second mask layer. There is a one-to-one correspondence between the microlenses and the first and second openings. The optical construction includes an intermediate layer disposed between the structured first major surface and the first mask layer and including an undulating second major surface facing, and in substantial registration with, an undulating third major surface of first mask layer so as to define a substantially uniform spacing therebetween.

Abstract: A charge-modified particle comprising the inorganic core and a shell surrounding the inorganic core, wherein the shell comprises a copolymer comprising monomeric units corresponding to free-radically polymerizable monomers, and wherein at least one of the monomeric units comprises a substituted benzotriazolylphenolate salt. Methods of making the charge-modified particle by admicellar polymerization are also disclosed.

Abstract: The present invention is a multi-component fiber includes a core and a sheathing surrounding the core. The core includes a first aliphatic polyester or copolymer of an aliphatic polyester. The sheathing includes a second aliphatic polyester or copolymer of an aliphatic polyester or a polyamide, and a hydrophobic agent. The second aliphatic polyester or copolymer of an aliphatic polyester or a polyamide has a melt flow index of between about 0.5 and about 19.5 g/10 min using a 2.16 Kg weight at 190° C.

Abstract: Structures and methods for reducing the thermal resistance of quantum cascade laser (QCL) devices and QCL-based photonic integrated circuits (QCL-PIC) are provided. In various embodiments, the native substrate of QCL and QCL-PIC devices is replaced with a foreign substrate that has very high thermal conductivity, for example, using wafer bonding methods. In some examples, wafer bonding of processed, semi-processed, or unprocessed QCL and QCL-PIC epilayers or devices on their native substrate to a high-thermal-conductivity substrate is performed, followed by removal of the native substrate via selective etching, and performing additional device processing if necessary. Thereafter, in some embodiments, cleaving or dicing individual devices from the bonded wafers may be performed, for example, for mounting onto heat sinks.

Abstract: An air filter media (10) including a pleated fibrous filtration web (8) with a first major side (2) that includes at least one sorbent-loaded area (26) in which sorbent particles (14) are present on a first major surface (25) of the pleated fibrous filtration web (8), at least some of the sorbent particles (14) being post-pleat-deposited sorbent particles.

Abstract: A photonic integrated circuit device includes a passive waveguide section formed over a substrate, a quantum cascade laser (QCL) gain section formed over the substrate and adjacent to the passive waveguide section, and a taper section disposed between and in contact with each of the passive waveguide section and the QCL gain section. In some embodiments, the passive waveguide section includes a passive waveguide core layer disposed between a first cladding layer and a second cladding layer. In some examples, the QCL gain section includes a QCL active region disposed between a first confinement layer and a second confinement layer, where the QCL active region has a lower index of refraction than each of the first and second confinement layers. In some embodiments, the taper section is configured to optically couple the QCL gain section to the passive waveguide section.

Abstract: A charge-modified particle comprising the inorganic core and a shell surrounding the inorganic core, wherein the shell comprises a copolymer comprising monomeric units corresponding to free-radically polymerizable monomers, and wherein at least one of the monomeric units comprises a substituted benzotriazolylphenolate salt. Methods of making the charge-modified particle by admicellar polymerization are also disclosed.

Abstract: The present disclosure provides a core-sheath filament. The core-sheath filament includes an adhesive core and a non-tacky sheath, wherein the sheath exhibits a melt flow index of less than 15 grams per 10 minutes. The present disclosure also provides a method of printing an adhesive. The method includes a) melting a core-sheath filament in a nozzle to form a molten composition, and b) dispensing the molten composition through the nozzle onto a substrate. Steps a) and b) are carried out one or more times to form a printed adhesive. The core-sheath filament includes an adhesive core and a non-tacky sheath. Further, methods are provided, including receiving, by a manufacturing device having one or more processors, a digital object comprising data specifying an article; and generating, with the manufacturing device by an additive manufacturing process using a core-sheath filament, the article including a printed adhesive based on the digital object.

Abstract: A photonic integrated circuit device includes a passive waveguide section formed over a substrate, a quantum cascade laser (QCL) gain section formed over the substrate and adjacent to the passive waveguide section, and a taper section disposed between and in contact with each of the passive waveguide section and the QCL gain section. In some embodiments, the passive waveguide section includes a passive waveguide core layer disposed between a first cladding layer and a second cladding layer. In some examples, the QCL gain section includes a QCL active region disposed between a first confinement layer and a second confinement layer, where the QCL active region has a lower index of refraction than each of the first and second confinement layers. In some embodiments, the taper section is configured to optically couple the QCL gain section to the passive waveguide section.

Abstract: An air filter media (10) including a pleated fibrous filtration web (8) with a first major side (2) that includes at least one sorbent-loaded area (26) in which sorbent particles (14) are present on a first major surface (25) of the pleated fibrous filtration web (8), at least some of the sorbent particles (14) being post-pleat-deposited sorbent particles.

Abstract: Aspects of the present disclosure relate to a multicomponent filament and articles thereof. The multicomponent filament comprises at least a first component and a second component. The first component includes a thermoplastic polymer. The second component includes a hydrophilic thermoplastic polymer comprising 65% (w/w) to 90% (w/w) (inclusive) hydrophilic segments. The first component is capable of forming a continuous filament with the second component.

Abstract: Provided are methods and related compositions for separating immiscible organic and aqueous compositions. The methods include dispersing a discrete, insoluble filler in the organic composition, dispersing the organic composition into the aqueous composition, separating under gravity the organic and aqueous compositions into respective upper and lower layers. Advantageously, the insoluble filler remains in the organic composition and facilitates segregation and coalescence of droplets of the organic composition in the aqueous composition.

Abstract: A nonlinear metasurface structure including a multi-quantum-well layer designed for a nonlinear response for a desired nonlinear optical process and an array of nanoantennas coupled to the intersubband transitions of the multi-quantum-well layer. Each nanoantenna in the array is designed to have electromagnetic resonances at or close to all input and output frequencies of a given nonlinear optical process. Nanoantennas allow efficient coupling of any incident and outgoing light polarizations to intersubband transitions. Nanoantennas may further provide significant field enhancement in the multi-quantum-well layer. As a result, the nonlinear metasurface structure can be designed to produce a highly nonlinear response for any polarization and angle of incidence of incoming and outgoing waves in a nonlinear optical process. Due to their very larger nonlinear response, efficient frequency conversion can be produced in these metasurfaces without the stringent phase-matching constraints of bulk nonlinear crystals.

Abstract: A terahertz source implementing a {hacek over (C)}erenkov difference-frequency generation scheme in a quantum cascade laser. The laser includes an undoped or semi-insulating InP substrate with an exit facet that is polished at an angle between 10° to 40°. The laser further includes a first waveguide cladding layer(s) in contact with an active layer (arranged as a multiple quantum well structure) and a current extraction layer on top of the substrate. Furthermore, the laser includes a second waveguide cladding layer(s) on top of the active layer, where the first and second waveguide cladding layers are disposed to form a waveguide structure by which terahertz radiation generated in the active layer is guided inside the laser. The terahertz radiation is emitted into the substrate at a {hacek over (C)}erenkov angle relative to a direction of the nonlinear polarization wave in the active layer, and once in the substrate, propagates towards the exit facet.

Abstract: A nonlinear metasurface structure including a multi-quantum-well layer designed for a nonlinear response for a desired nonlinear optical process and an array of nanoantennas coupled to the intersubband transitions of the multi-quantum-well layer. Each nanoantenna in the array is designed to have electromagnetic resonances at or close to all input and output frequencies of a given nonlinear optical process. Nanoantennas allow efficient coupling of any incident and outgoing light polarizations to intersubband transitions. Nanoantennas may further provide significant field enhancement in the multi-quantum-well layer. As a result, the nonlinear metasurface structure can be designed to produce a highly nonlinear response for any polarization and angle of incidence of incoming and outgoing waves in a nonlinear optical process. Due to their very larger nonlinear response, efficient frequency conversion can be produced in these metasurfaces without the stringent phase-matching constraints of bulk nonlinear crystals.

Abstract: A terahertz difference-frequency generation quantum cascade laser source that provides monolithic, electrically-controlled tunable terahertz emission. The quantum cascade laser includes a substrate, a lower cladding layer positioned above the substrate and an active region layer with optical nonlinearity positioned on the lower cladding layer. The active region layer is arranged as a multiple quantum well structure. One or more feedback gratings are etched into spatially separated sections of the cladding layer positioned on either side of the active region. The periodicity of each grating section determines the mid-infrared lasing frequencies. The grating sections are electrically isolated from one another and biased independently. Tuning is achieved by changing a refractive index of one or all of the grating sections via a DC current bias thereby causing a shift in the mid-infrared lasing frequency. In this manner, a monolithic, electrically-pumped, tunable THz source is achieved.

Abstract: Methods and systems include generating one or more mid-infrared frequencies based at least upon electron transitions in one or more quantum cascade heterostructures. The quantum cascade heterostructures are concurrently configured with a significant second-order nonlinear susceptibility, a significant third-order nonlinear susceptibility, and an insignificant group velocity dispersion. A set of mid-infrared frequencies (that may include a frequency comb) is generated in the quantum cascade heterostructures based at least upon a four-wave mixing of the one or more mid-infrared frequencies. The four-wave mixing arises at least from the significant third-order nonlinear susceptibility and the insignificant group velocity dispersion. A set of terahertz frequencies (that may include a frequency comb) is generated in the quantum cascade heterostructures based at least upon a difference frequency generation from mid-infrared frequency pairs selected from the set of mid-infrared frequencies.

Abstract: A terahertz source implementing a {hacek over (C)}erenkov difference-frequency generation scheme in a quantum cascade laser. The laser includes an undoped or semi-insulating InP substrate with an exit facet that is polished at an angle between 10° to 40°. The laser further includes a first waveguide cladding layer(s) in contact with an active layer (arranged as a multiple quantum well structure) and a current extraction layer on top of the substrate. Furthermore, the laser includes a second waveguide cladding layer(s) on top of the active layer, where the first and second waveguide cladding layers are disposed to form a waveguide structure by which terahertz radiation generated in the active layer is guided inside the laser. The terahertz radiation is emitted into the substrate at a {hacek over (C)}erenkov angle relative to a direction of the nonlinear polarization wave in the active layer, and once in the substrate, propagates towards the exit facet.

Abstract: Methods and systems include generating one or more mid-infrared frequencies based at least upon electron transitions in one or more quantum cascade heterostructures. The quantum cascade heterostructures are concurrently configured with a significant second-order nonlinear susceptibility, a significant third-order nonlinear susceptibility, and an insignificant group velocity dispersion. A set of mid-infrared frequencies (that may include a frequency comb) is generated in the quantum cascade heterostructures based at least upon a four-wave mixing of the one or more mid-infrared frequencies. The four-wave mixing arises at least from the significant third-order nonlinear susceptibility and the insignificant group velocity dispersion. A set of terahertz frequencies (that may include a frequency comb) is generated in the quantum cascade heterostructures based at least upon a difference frequency generation from mid-infrared frequency pairs selected from the set of mid-infrared frequencies.