Abstract: Reversible phase-change materials (PCMs) can be added to or incorporated into meta-lenses, wave plates, waveguides, gratings, and other optical components to form active optical devices with controllable and adjustable optical characteristics. Local heating can be used to induce solid-state phase changes and large refractive index changes in the PCMs. The phase and index changes can provide large changes in the device's optical characteristics. Optical devices with PCM can be used for imaging applications, orbital angular momentum control, photonic integrated circuits and optical communication systems, beam steering, and other application.

Abstract: An optical coherence tomography (OCT) engine includes a digital Fourier-Transform (dFT) spectrometer, a tunable delay line, and a high-speed optical phased array (OPA) scanner integrated onto a single chip. The broadband dFT spectrometer offers superior signal-to-noise ratio (SNR) and fine axial resolution; the tunable delay line ensures large imaging depth by circumventing sensitivity roll-off; and the OPA can scan the beams at GHz rates without moving parts. Unlike conventional spectrometers, the dFT spectrometer employs an optical switch network to retrieve spectral information in an exponentially scaling fashion—its performance doubles with every new optical switch added to the network. Moreover, it also benefits from the Fellgett's advantage, which provide a significant SNR edge over conventional spectrometers. The tunable delay line balances the path length difference between the reference and sample arms, avoiding any need to sample high-frequency spectral fringes.

Abstract: Meta-lens based ocular imaging, near-eye display, and eye-tracking systems are described. The systems can include a single focusing optic and an integrated circuit that provides illumination light and includes an imaging array. The focusing optic includes meta-atoms formed on a substrate. The systems may have no moving parts and achieve imaging or image-projection fields-of-view approaching or exceeding 180 degrees. Because of their low part count, the systems can be robust and have a very small form factor.

Abstract: Disclosed are methods and systems for desulfurization of CO-rich streams. A method can include contacting a CO-rich gas stream with activated carbon and/or contacting the CO-rich gas stream with a zinc-oxide sorbent material at a temperature of 0 to 50° C. to remove at least a portion of the sulfur-containing compounds present in the stream.

Abstract: Wide-angle optical functionality is beneficial for imaging and image projection devices. Conventionally, wide-angle operation is attained by a complicated assembly of optical elements. Recent advances have led to meta-surface lenses or meta-lenses, which are ultra-thin planar lenses with nanoantennas that control the phase, amplitude, and/or polarization of light. Here, we present a meta-lens capable of diffraction-limited focusing and imaging over an unprecedented >170° angular field of view (FOV). The lens is integrated on a one-piece flat substrate and includes an aperture on one side and a single meta-surface on the other side. The meta-surface corrects third-order Seidel aberrations, including coma, astigmatism, and field curvature. The meta-lens has a planar focal plane, which enables considerably simplified system architectures for imaging and projection.

Abstract: Wide-angle optical functionality is beneficial for imaging and image projection devices. Conventionally, wide-angle operation is attained by a complicated assembly of optical elements. Recent advances have led to meta-surface lenses or meta-lenses, which are ultra-thin planar lenses with nanoantennas that control the phase, amplitude, and/or polarization of light. Here, we present a meta-lens capable of diffraction-limited focusing and imaging over an unprecedented >170° angular field of view (FOV). The lens is integrated on a one-piece flat substrate and includes an aperture on one side and a single meta-surface on the other side. The meta-surface corrects third-order Seidel aberrations, including coma, astigmatism, and field curvature. The meta-lens has a planar focal plane, which enables considerably simplified system architectures for imaging and projection.

Abstract: A method of autothermal oxidative coupling of methane (OCM) utilizes introducing a methane-containing feedstock and an oxygen-gas-containing feedstock into a reactor (10) as a flowing mixture (18) with a space time of 500 ms or less. The reactor (10) contains a catalyst bed (20) of an OCM catalyst that contacts the flowing mixture and wherein the catalyst bed (20) has a heat Peclet number (Peh) of from 5 or less, a mass Peclet number (Pem) of from 5 or more, and a transverse Peclet number (P) of from 1 or less while contacting the flowing mixture. The methane and oxygen of the feedstocks are allowed to react within the reactor (10) to form methane oxidative coupling reaction products. A reactor (10) for carrying out the OCM reaction is also disclosed.

Abstract: A method of autothermal oxidative coupling of methane (OCM) utilizes introducing a methane-containing feedstock and an oxygen-gas-containing feedstock into a reactor (10) as a flowing mixture (18) with a space time of 500 ms or less. The reactor (10) contains a catalyst bed (20) of an OCM catalyst that contacts the flowing mixture and wherein the catalyst bed (20) has a heat Peclet number (Peh) of from 5 or less, a mass Peclet number (Pem) of from 5 or more, and a transverse Peclet number (P) of from 1 or less while contacting the flowing mixture. The methane and oxygen of the feedstocks are allowed to react within the reactor (10) to form methane oxidative coupling reaction products. A reactor (10) for carrying out the OCM reaction is also disclosed.

Abstract: Wide-angle optical functionality is beneficial for imaging and image projection devices. Conventionally, wide-angle operation is attained by a complicated assembly of optical elements. Recent advances have led to meta-surface lenses or meta-lenses, which are ultra-thin planar lenses with nanoantennas that control the phase, amplitude, and/or polarization of light. Here, we present a meta-lens capable of diffraction-limited focusing and imaging over an unprecedented >170° angular field of view (FOV). The lens is integrated on a one-piece flat substrate and includes an aperture on one side and a single meta-surface on the other side. The meta-surface corrects third-order Seidel aberrations, including coma, astigmatism, and field curvature. The meta-lens has a planar focal plane, which enables considerably simplified system architectures for imaging and projection.

Abstract: Disclosed herein are systems and processes for the conversion of a methane feedstock to C2+ hydrocarbons.

Abstract: State-of-the-art portable Raman spectrometers use discrete free-space optical components that must be aligned well and that don't tolerate vibrations well. Conversely, the inventive spectrometers are made with monolithic photonic integration to fabricate some or all optical components on one or more planar substrates. Photonic integration enables dense integration of components, eliminates manual alignment and individual component assembly, and yields superior mechanical stability and resistance to shock or vibration. These features make inventive spectrometers especially suitable for use in high-performance portable or wearable sensors. They also yield significant performance advantages, including a large (e.g., 10,000-fold) increase in Raman scattering efficiency resulting from on-chip interaction of the tightly localized optical mode and the analyte and a large enhancement in spectral resolution and sensitivity resulting from the integration of an on-chip Fourier-transform spectrometer.

Abstract: A spectrometer includes an interferometer having a first interference arm and a second interference arm to produce interference patterns from incident light. At least one of the interference arms includes a series of cascaded optical switches connected by two (or more) waveguides of different lengths. Each optical switch directs the incident light into one waveguide or another, thereby changing the optical path length difference between the first interference arm and the second interference arm. This approach can be extended to multi-mode incident light by placing parallel interferometers together, each of which performs spectroscopy of one single mode in the multi-mode incident light. To maintain the compactness of the spectrometer, adjacent interferometers can share one interference arm.

Abstract: An alloy of GexSbySezTem includes atoms of Ge, Sb, Se, and Te that form a crystalline structure having a plurality of vacancies randomly distributed in the crystalline structure. The alloy can be used to construct an optical device including a first waveguide to guide a light beam and a modulation layer disposed on the first waveguide. The modulation includes the alloy of GexSbySezTem which has a first refractive index n1 in an amorphous state and a second refractive index n2, greater than the first refractive index by at least 1, in a crystalline state. The first waveguide and the modulation layer are configured to guide about 1% to about 50% of the light beam in the modulation layer when the alloy is in the amorphous state and guide no optical mode when the alloy is in the crystalline state.

Abstract: State-of-the-art portable Raman spectrometers use discrete free-space optical components that must be aligned well and that don't tolerate vibrations well. Conversely, the inventive spectrometers are made with monolithic photonic integration to fabricate some or all optical components on one or more planar substrates. Photonic integration enables dense integration of components, eliminates manual alignment and individual component assembly, and yields superior mechanical stability and resistance to shock or vibration. These features make inventive spectrometers especially suitable for use in high-performance portable or wearable sensors. They also yield significant performance advantages, including a large (e.g., 10,000-fold) increase in Raman scattering efficiency resulting from on-chip interaction of the tightly localized optical mode and the analyte and a large enhancement in spectral resolution and sensitivity resulting from the integration of an on-chip Fourier-transform spectrometer.

Abstract: Reflecting light beams off of microscale three-dimensional (3D) freeform surfaces can yield highly efficient coupling into and out of optical waveguides, optical fibers, and photonic chips. The structure of the 3D freeform reflective surface determines the shape of the reflected beam. This allows freeform reflectors to control the mode profile, rotation angle, and divergence angle of light beams. Control of beam shape enables mode matching between source output mode and target input mode, which results in low-loss optical coupling. An inventive freeform reflective surface can direct light beams in plane or out of plane via specular reflection or total internal reflection. A photonic integrated circuit with this type of freeform optical coupler can operate with a bandwidth range of at least 400 nm, potentially encompassing all visible or telecommunications wavelengths, and can be volume manufactured in photonic chips.

Abstract: An optical interconnect system has first and second waveguides each with wedge-shaped cross-section at a first end, disposed over an optical modulator. The optical modulator is a surface-plasmon multi quantum well (SP-MQW) modulator, the first waveguide an input waveguide and the second waveguide configured an output waveguide. In embodiments the SP-MQW modulator has multiple semiconductor layers disposed atop a lower metal layer between 10 and 300 nanometers thick and configured such that incident light is reflected at the lower metal layer unless a voltage is applied to the semiconductor layers, when incident light is coupled into a surface plasmon mode in the lower metal layer.

Abstract: An optical device as described herein includes a host substrate fabricated from a dielectric material transparent in the Infrared range. Additionally, the optical device as discussed herein includes multiple elements disposed on the host substrate. The multiple elements are spaced apart from each other on the host substrate in accordance with a desired pattern. Each of the multiple elements disposed in the host substrate is fabricated from a second material having a refractive index of greater than 4.5. Such an optical device provides an improvement over conventional optical devices that operate in the Infrared range.

Abstract: An alloy of GexSbySezTem includes atoms of Ge, Sb, Se, and Te that form a crystalline structure having a plurality of vacancies randomly distributed in the crystalline structure. The alloy can be used to construct an optical device including a first waveguide to guide a light beam and a modulation layer disposed on the first waveguide. The modulation includes the alloy of GexSbySezTem which has a first refractive index n1 in an amorphous state and a second refractive index n2, greater than the first refractive index by at least 1, in a crystalline state. The first waveguide and the modulation layer are configured to guide about 1% to about 50% of the light beam in the modulation layer when the alloy is in the amorphous state and guide no optical mode when the alloy is in the crystalline state.

Abstract: A multi-channel optical imaging and stimulation system includes a light source to deliver light beams into a light guide. Different light beams are coupled into different spatial modes supported by the light guide. The light guide includes multiple segments, each of which defines a window to couple a specified group of spatial modes out of the light guide to illuminate or stimulate a target. Light reflected, scattered, or emitted by the target is also collected by the windows in the light guide. The light collected by different windows is detected by different pixels of a detector, thereby creating a correspondence between the pixel location and the spatial location of site at which the light is collected. An image of the target is then reconstructed based on this correspondence.

Abstract: An apparatus for generating a spectral image includes a filter to receive incident light. The filter has a variable refractive index. The apparatus also includes a modulator, operably coupled to the filter, to modulate the variable refractive index of the filter so as to generate a plurality of optical patterns from the incident light. The plurality of optical patterns represents the spectral image and each optical pattern in the plurality of optical patterns corresponds to a different modulation of the variable refractive index. The apparatus further includes a detector, in optical communication with the filter, to detect the plurality of optical patterns.