Spin to orbital angular momentum transfer in frequency up-conversion

We demonstrate the spin to orbital angular momentum transfer in frequency upconversion with structured light beams. A vector vortex is coupled to a circularly polarized Gaussian beam in noncollinear second harmonic generation under type-II phase match. The second harmonic beam inherits the Hermite–Gaussian components of the vector vortex; however, the relative phase between them is determined by the polarization state of the Gaussian beam. This effect creates an interesting crosstalk between spin and orbital degrees of freedom, allowing the angular momentum transfer between them. Our experimental results match the theoretical predictions for the nonlinear optical response.

MEMS microphone intensity array for cabin noise measurements

Aircraft cabin noise measurements in flight are used toto quantify the noise level, and to identify the entry point of acoustic energy into the cabin. Sound intensity probes are the state-of-the-art measurement technique for this task. During measurements, additional sound absorbing material is used to ease the rather harsh acoustic measurement environment inside the cabin. In order to decrease the expensive in-flight measurement time, an intensity array approach was chosen. This intensity probe consists of 512 MEMS-Microphones. Depending on the frequency, these microphones can be combined as an array of hundreds of 3D- intensity probes. The acoustic velocity is estimated using a high order 3D finite difference stencil. At low frequencies, a larger spacing is used to reduce the requirement of accurate phase match of the microphone sensors. Measurements were conducted in the ground-based Dornier 728 cabin noise simulation as well as in-flight.

A Binocular Vision-Based 3D Sampling Moiré Method for Complex Shape Measurement

As a promising method for moiré processing, sampling moiré has attracted significant interest for binocular vision-based 3D measurement, which is widely used in many fields of science and engineering. However, one key problem of its 3D shape measurement is that the visual angle difference between the left and right cameras causes inconsistency of the fringe image carrier fields, resulting in the phase mismatch of sampling moiré. In this paper, we developed a phase correction method to solve this problem. After epipolar rectification and carrier phase introduction and correction, the absolute phase of the fringe images was obtained. A more universal 3D sampling moiré measurement can be achieved based on the phase match and binocular vision model. Our numerical simulation and experiment showed the high robustness and anti-noise ability of this new 3D sampling moiré method for high-precision 3D shape measurement. As an application, cantilever beams are fabricated by directed energy deposition (DED) using different process parameters, and their 3D deformation caused by residual stresses is measured, showing great potential for residual stress analyses during additive manufacturing.

Subsurface Back Allocation: Calculating Production and Injection Allocation by Layer in a Multilayered Waterflood Using a Combination of Machine Learning and Reservoir Physics

Allocation of injection and production by layer is required for several production and reservoir engineering workflows including reserves estimation, water injection conformance, identification of workover and infill drilling candidates, etc. In cases of commingled production, allocation to layers is unknown; running production logging tools is expensive and not always possible. The current industry practice utilizes simplified approaches such as K*H based allocation which provides a static and inaccurate approximation of the allocation factors; this manual approach requires trial and error and can take several weeks in complex fields. This paper presents a novel technique to solve this problem using a combination of reservoir physics and machine learning. The methodology is made up of four stages: Data Entry: includes production at well level (commingled), injection at layer level and injection patterns or a connectivity map (optional) Gross Match: in order to match gross production for each well, the tool solves for time-varying layer-level injection allocation factors using a total material balance equation across all wells. Phase Match: having the allocation factors from the previous step, the tool automatically tunes various petrophysical parameters (i.e. porosity, relative permeability, etc.) in the physics model for each injector-producer pair across all the connected layers to match the oil and water production in each producer. An ensemble of several models can be run simultaneously to account for the probabilistic nature of the problem. Output: The steps 2 and 3 can be performed at pattern level for all connected patterns or for the whole field. The application of the technology in a complex field with 80+ layers in Southern Argentina is demonstrated as a case study of the benefits of the adoption of the technology.

Coherent amplification and inversion less lasing of surface plasmon polaritons in a negative index metamaterial with a resonant atomic medium

Surface plasmon polaritons (SPPs) lasing requires population inversion, it is inefficient and possesses poor spectral properties. We develop an inversion-less concept for a quantum plasmonic waveguide that exploits unidirectional superradiant SPP (SSPP) emission of radiation to produce intense coherent surface plasmon beams. Our scheme includes a resonantly driven cold atomic medium in a lossless dielectric situated above an ultra-low loss negative index metamaterial (NIMM) layer. We propose generating unidirectional superradiant radiation of the plasmonic field within an atomic medium and a NIMM layer interface and achieve amplified SPPs by introducing phase-match between the superradiant SPP wave and coupled laser fields. We also establish a parametric resonance between the weak modulated plasmonic field and the collective oscillations of the atomic ensemble, thereby suppressing decoherence of the stably amplified directional polaritonic mode. Our method incorporates the quantum gain of the atomic medium to obtain sufficient conditions for coherent amplification of superradiant SPP waves, and we explore this method to quantum dynamics of the atomic medium being coupled with the weak polaritonic waves. Our waveguide configuration acts as a surface plasmon laser and quantum plasmonic transistor and opens prospects for designing controllable nano-scale lasers for quantum and nano-photonic applications.

Discovery of a Two-Dimensional Type I Superionic Conductor

<div> <div> <div> <p>Type I superionic conductors (e.g., AgI, Ag₂Se, etc.) are defined by an abrupt transition to the superionic state and have so far been found exclusively in 3D crystal structures. Here, we reveal a new 2D type I superionic conductor, α-KAg₃Se₂ by total scattering techniques and complementary simulations. Quasi-elastic neutron scattering (QENS) from the high temperature superionic phase match a simple Fickian diffusion mechanism with a diffusion coefficient of ~10^-5 cm² s^-1 between 710 and 740 K. Ab initio molecular dynamics simulations confirm that the mobile Ag⁺ ions are confined to 4 Å thick layers, in addition to reproducing the experimental diffusion coefficient from QENS and the local structure obtained from X-ray powder pair-distribution-function analysis. Finally, chemical substitutions suggest that the nature of alkali metal ions comprising the charge-balancing layers can facilitate or inhibit the phase transition temperature. </p> </div> </div> </div>

Discovery of a Two-Dimensional Type I Superionic Conductor

<div> <div> <div> <p>Type I superionic conductors (e.g., AgI, Ag₂Se, etc.) are defined by an abrupt transition to the superionic state and have so far been found exclusively in 3D crystal structures. Here, we reveal a new 2D type I superionic conductor, α-KAg₃Se₂ by total scattering techniques and complementary simulations. Quasi-elastic neutron scattering (QENS) from the high temperature superionic phase match a simple Fickian diffusion mechanism with a diffusion coefficient of ~10^-5 cm² s^-1 between 710 and 740 K. Ab initio molecular dynamics simulations confirm that the mobile Ag⁺ ions are confined to 4 Å thick layers, in addition to reproducing the experimental diffusion coefficient from QENS and the local structure obtained from X-ray powder pair-distribution-function analysis. Finally, chemical substitutions suggest that the nature of alkali metal ions comprising the charge-balancing layers can facilitate or inhibit the phase transition temperature. </p> </div> </div> </div>

Discovery of a Two-Dimensional Type I Superionic Conductor

<div> <div> <div> <p>Type I superionic conductors (e.g., AgI, Ag2Se, etc.) are defined by an abrupt transition to the superionic state and have so far been found exclusively in 3D crystal structures. Here, we reveal a new 2D type I superionic conductor, α-KAg3Se2 by total scattering techniques and complementary simulations. Quasi-elastic neutron scattering (QENS) from the high temperature superionic phase match a simple Fickian diffusion mechanism with a diffusion coefficient of ~10-5 cm2 s-1 between 710 and 740 K. Ab initio molecular dynamics simulations confirm that the mobile Ag+ ions are confined to 4 Å thick layers, in addition to reproducing the experimental diffusion coefficient from QENS and the local structure obtained from X-ray powder pair-distribution-function analysis. Finally, chemical substitutions suggest that the nature of alkali metal ions comprising the charge-balancing layers can facilitate or inhibit the phase transition temperature. </p> </div> </div> </div>