Stratified Volume Research Articles

Quantum annealing-aided design of an ultrathin-metamaterial optical diode

Thin-film optical diodes are important elements for miniaturizing photonic systems. However, the design of optical diodes relies on empirical and heuristic approaches. This poses a significant challenge for identifying optimal structural models of optical diodes at given wavelengths. Here, we leverage a quantum annealing-enhanced active learning scheme to automatically identify optimal designs of 130 nm-thick optical diodes. An optical diode is a stratified volume diffractive film discretized into rectangular pixels, where each pixel is assigned to either a metal or dielectric. The proposed scheme identifies the optimal material states of each pixel, maximizing the quality of optical isolation at given wavelengths. Consequently, we successfully identify optimal structures at three specific wavelengths (600, 800, and 1000 nm). In the best-case scenario, when the forward transmissivity is 85%, the backward transmissivity is 0.1%. Electromagnetic field profiles reveal that the designed diode strongly supports surface plasmons coupled across counterintuitive metal–dielectric pixel arrays. Thereby, it yields the transmission of first-order diffracted light with a high amplitude. In contrast, backward transmission has decoupled surface plasmons that redirect Poynting vectors back to the incident medium, resulting in near attenuation of its transmission. In addition, we experimentally verify the optical isolation function of the optical diode.

3D Visualization Techniques for Analysis and Archaeological Interpretation of GPR Data

The non-invasive detection and digital documentation of buried archaeological heritage by means of geophysical prospection is increasingly gaining importance in modern field archaeology and archaeological heritage management. It frequently provides the detailed information required for heritage protection or targeted further archaeological research. High-resolution magnetometry and ground-penetrating radar (GPR) became invaluable tools for the efficient and comprehensive non-invasive exploration of complete archaeological sites and archaeological landscapes. The analysis and detailed archaeological interpretation of the resulting large 2D and 3D datasets, and related data from aerial archaeology or airborne remote sensing, etc., is a time-consuming and complex process, which requires the integration of all data at hand, respective three-dimensional imagination, and a broad understanding of the archaeological problem; therefore, informative 3D visualizations supporting the exploration of complex 3D datasets and supporting the interpretative process are in great demand. This paper presents a novel integrated 3D GPR interpretation approach, centered around the flexible 3D visualization of heterogeneous data, which supports conjoint visualization of scenes composed of GPR volumes, 2D prospection imagery, and 3D interpretative models. We found that the flexible visual combination of the original 3D GPR datasets and images derived from the data applying post-processing techniques inspired by medical image analysis and seismic data processing contribute to the perceptibility of archaeologically relevant features and their respective context within a stratified volume. Moreover, such visualizations support the interpreting archaeologists in their development of a deeper understanding of the complex datasets as a starting point for and throughout the implemented interactive interpretative process.

Numerical Study on Non-Uniform Temperature Distribution and Thermal Performance of Plate Heat Exchanger

In this study, computational fluid dynamics (CFD) analysis was performed to investigate the cause of the thermal stratification in the channel and the temperature non-uniformity of the plate heat exchanger. The flow velocity maldistribution of the channel and the merging parts caused temperature non-uniformity in the channel width direction. The non-uniformity of flow velocity and temperature in the channel is shown in Section 1 > Section 3 > Section 2 from the heat exchanger. The non-uniform temperature distribution in the channel caused channel stratification and non-uniform outlet temperature. Stratification occurred at the channel near the merging due to the flow rate non-uniformity in the channel. In particular, as the mass flow rate increased from 0.03 to 0.12 kg/s and the effectiveness increased from 0.436 to 0.615, the cold-side stratified volume decreased from 4.06 to 3.7 cm3, and the temperature difference between the stratified area and the outlet decreased from 1.21 K to 0.61 K. The increase in mass flow and the decrease in temperature difference between the cold and hot sides alleviated the non-uniformity of the outlet temperature due to the increase in effectiveness. Besides, as the inlet temperature difference between the cold and the hot side increases, the temperature non-uniformity at the outlet port is poor due to the increase in the stratified region at the channel, and the distance to obtain a uniform temperature in the outlet pipe increases as the temperature at the hot side increases.

Blazar variability power spectra from radio up to TeV photon energies: Mrk 421 and PKS 2155−304

ABSTRACT We present the results of the power spectral density (PSD) analysis for the blazars Mrk 421 and PKS 2155−304, using good-quality, densely sampled light curves at multiple frequencies, covering 17 decades of the electromagnetic spectrum, and variability time-scales from weeks up to a decade. The data were collected from publicly available archives of observatories at radio from Owens Valley Radio Observatory, optical and infrared (B, V, R, I, J, H, and Kbands), X-rays from the Swift and the Rossi X-ray Timing Explorer, high and very high energy (VHE) γ-rays from the Fermi and Very Energetic Radiation Imaging Telescope Array System as well as the High Energy Stereoscopic System. Our results are: (1) the power-law form of the variability power spectra at radio, infrared, and optical frequencies have slopes ∼1.8, indicative of random-walk-type noise processes; (2) the power-law form of the variability power spectra at higher frequencies, from X-rays to VHE γ-rays, however, have slopes ∼1.2, suggesting a flicker noise-type process; and (3) there is significantly more variability power at X-rays, high and VHE γ-rays on time-scales ≲ 100 d, as compared to lower energies. Our results do not easily fit into a simple model, in which a single compact emission zone is dominating the radiative output of the blazars across all the time-scales probed in our analysis. Instead, we argue that the frequency-dependent shape of the variability power spectra points out a more complex picture, with highly inhomogeneous outflow producing non-thermal emission over an extended, stratified volume.

Fixed and Variable Relationship Models to Define the Volume-Value Relationship in Spinal Fusion Surgery: A Macroeconomic Analysis Using Evidence-Based Thresholds.

ObjectiveIncreased surgical volume has been associated with improved patient outcomes at the surgeon and hospital level. To date, clinically meaningful stratified volume benchmarks have yet to be defined for surgeons or hospitals in the context of spinal fusion surgery. The objective of this study was to establish evidence-based thresholds using outcomes and cost to stratify surgeons and hospitals performing spinal fusion surgery by volume. MethodsUsing 155,788 patients undergoing spinal fusion surgery, we created and applied 4 models using stratum-specific likelihood ratio (SSLR) analysis of a receiver operating characteristic (ROC) curve. This statistical approach was used to generate 4 sets of volume thresholds predictive of increased length of stay (LOS) and increased cost for surgeons and hospitals. ResultsSSLR analysis of the 2 ROC curves by annual surgical volume produced 3 or 4 distinct volume categories. Analysis of LOS by annual surgeon spinal fusion volume produced 4 strata: low, medium, high, and very high. Analysis of LOS by annual hospital spinal fusion volume produced 3 strata: low, medium, and high. No relationship between volume and cost could be clearly defined based on the generation of ROC curves for surgeons or hospitals offering spinal fusion. ConclusionThis study used evidence-based thresholds to identify a direct, variable relationship model between volume and outcomes of spinal fusion surgery, using LOS as a surrogate, for both surgeons and hospitals. A fixed relationship model was identified between surgeon and hospital volume and cost, as no statistically meaningful relationship could be established.

Abstract 3916: Relationship of guanylyl cyclase C (GCC) expression and efficacy of TAK-164, a GCC-targeted antibody-drug conjugate in a panel of 68 subcutaneous HuPrime colorectal cancer PDX models

Abstract Guanylyl cyclase C (GCC) is a cell surface protein expressed in more than 95% of metastatic colorectal cancers and in the majority of gastric and pancreatic cancers, making GCC an attractive antibody-drug conjugate (ADC) target. TAK-164 is an ADC comprised of a full-length, fully human IgG1 monoclonal antibody (mAb) directed toward the extracellular domain of GCC. The mAb is conjugated using ImmunoGen's peptide-linked indolinobenzodiazepine DNA alkylator DGN549. Previously presented preclinical studies using TAK-164 have demonstrated in vivo efficacy in a select number of GCC-expressing tumor models following a single administration of TAK-164. Here, we describe the selection of an appropriate dose for broad testing in a panel of patient-derived xenograft models of colorectal cancer. The efficacy data generated following a single administration of 15 µg/kg TAK-164 (payload concentration) were compared with molecular features that could aid in understanding drivers of TAK-164 activity, including GCC expression by immunohistochemistry (IHC). Primary colorectal cancer models were derived from colorectal adenocarcinomas and implanted in immunocompromised mice. Once tumors reached a stratified mean volume of 150-250 mm3, animals were randomized into treatment groups (n = 1/group) and dosing was initiated on Day 0 of the study. There were three tumor groups (Vehicle treated, TAK-164 treated, and naïve), which were used to characterize genomic and molecular features of the model. The planned study endpoint was 60 days or until a humane endpoint was reached. For all models included in the study, an IHC assay to detect GCC was used to explore the relationship between GCC expression and time to rise (TTR), a preclinical tumor progression measurement. TTR is the Delta duration in days on study for each PDX model (TAK-164 - Vehicle) to reach 1000 mm3 tumor volume. In the present study, a mixed effects Cox regression analysis, using a continuous or binary stratification of GCC IHC expression, resulted in a statistically significant (p<0.05) increase in TTR in TAK-164−treated mice with higher expression levels of GCC. Ongoing analysis aims to better understand additional molecular drivers of TAK-164 treatment that may be useful for patient enrichment strategies in the clinic. TAK-164 is scheduled to enter phase I evaluation in 2018 in GCC-positive colorectal cancer and other GI malignancies. Citation Format: Erik M. Koenig, Cong Li, Huyuan Yang, Andy Zhu, Pooja Shah, Kazuho Nishimura, Bret Bannerman, Mengkun zhang, Bradley Stringer, Brittany Bahamon, O. Petter Veiby, Adnan Abu-Yousif. Relationship of guanylyl cyclase C (GCC) expression and efficacy of TAK-164, a GCC-targeted antibody-drug conjugate in a panel of 68 subcutaneous HuPrime colorectal cancer PDX models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3916.

利用多层体光栅产生飞秒脉冲串

利用多层体光栅产生飞秒脉冲串

Chirped pulse distortion in stratified volume reflection gratings

The problem of chirped pulse light Bragg diffraction by stratified volume reflection gratings is considered using characteristic matrix method. The spectral profiles of the transmitted and diffracted chirped pulses have been presented. Using these expressions the calculations of the diffracted spectra and diffraction efficiency have been made in the wide range of initial parameters of incident chirped pulse and the stratified volume reflection gratings. Variously shaped spectral distortions have been revealed and discussed based on these calculations.

Polychromatic low-coherence interferometry of stratified structures with digital interferogram recording and processing

The processes of formation and digital recording of interference patterns arising in partially coherent polychromatic light in the course of interference monitoring of surface microrelief in objects having stratified volume structure are considered. The expressions for the intensity distribution in the interference pattern depending on the surface relief and the object structure are derived taking the spectral properties of the photodetector array into account. The results of numerical simulation of interference fringes in polychromatic light and experimentally measured digital white light microinterferograms are presented. These results demonstrate the agreement between the theoretical model and the experimental interferograms and the possibility of solving the direct problem of low-coherence interferometry using numerical simulation of the interference pattern.

Spatiotemporal Sampling of Dynamic Environment Sequences

Environment sampling is a popular technique for rendering scenes with distant environment illumination. However, the temporal consistency of animations synthesized under dynamic environment sequences has not been fully studied. This paper addresses this problem and proposes a novel method, namely spatiotemporal sampling, to fully exploit both the temporal and spatial coherence of environment sequences. Our method treats an environment sequence as a spatiotemporal volume and samples the sequence by stratifying the volume adaptively. For this purpose, we first present a new metric to measure the importance of each stratified volume. A stratification algorithm is then proposed to adaptively suppress the abrupt temporal and spatial changes in the generated sampling patterns. The proposed method is able to automatically adjust the number of samples for each environment frame and produce temporally coherent sampling patterns. Comparative experiments demonstrate the capability of our method to produce smooth and consistent animations under dynamic environment sequences.

飞秒脉冲通过多层体光栅后的衍射光强分布

Based on the coupled-wave theory of single volume grating and matrix theory,the coupled-wave equation of stratified volume grating illuminated by femtosecond pulse is acquired.Solutions for the diffraction intensity spectrum and instantaneous diffraction intensity are obtained.The research results show that the diffraction characteristics depend on the parameters of the stratified gratings,such as the thickness of the buffer layers and grating layers,grating periods and the refractive index modulations of the grating.Through modulating these parameters,diffraction pulses with different shapes and bandwidths can be obtained.The results will be utilized to design devices employed in optical communication and pulse shaping.

Recursion formula for reflectance and the enhanced effect on the light group velocity control of the stratified and phase-shifted volume index gratings

We derived a recursion formula for the reflectance of the stratified and phase-shifted volume index gratings. The characteristics of the reflectance spectra of the stratified and phase-shifted volume index gratings were studied based on the recursion formula. It is shown that narrow bandwidth transparency peaks appear within the stop-band of the reflectance spectrum of the volume index gratings due to the intervention of the homogeneous buffer layers that induce the phase-shifts between neighboring volume index gratings. The spectral positions of the transparency peaks can be shifted within the stop-band by controlling the phase-shift, i.e., the buffer layer thickness. The described properties may find applications in addressable band-pass filter, switching, wavelength division multiplexing, and de-multiplexing. The dispersion near the transparency peaks of the stratified and phase-shifted volume index grating is found to be sharply enhanced as compared to the uniform volume index gratings. Significantly enhanced control on the group velocity of light by several orders of magnitude while keeping high transmittance is demonstrated in the stratified and phase-shifted volume index grating.

Anisotropic diffraction of stratified volume holographic grating in photorefractive media

We have studied the anisotropic diffraction properties of the stratified volume holographic gratings recorded in photorefractive media using the anisotropic coupled wave theory. It is shown that the diffraction efficiency of such system exhibit the uniform periodic Bragg selectivity properties. In addition the dependence of the stratified volume holographic optical elements (SVHOEs) diffraction properties on the buffer-layer thickness, grating-layer thickness, number of modulation layers, and total thickness of system are discussed in detail.

Fabrication and analysis of a three-layer stratified volume diffractive optical element high-efficiency grating

We have demonstrated a high-efficiency grating (>80%) using a three-layer Stratified Volume Diffractive Optical Element (SVDOE). Its angular sensitivity was measured optically and shown to agree extremely well with simulations performed using rigorous coupled wave analysis (RCWA). Further simulations predict an increase in efficiency as the number of layers is increased. An SVDOE consists of binary grating layers interleaved with homogeneous layers. The binary grating layers are shifted laterally relative to each other to emulate a volume holographic grating with slanted fringes. Creating the slanted fringe structure permits the preferred incidence angle of the SVDOE to be rotated to any arbitrary position. Achieving the relative offset between grating layers is the most challenging fabrication step and required the development of a high-precision alignment technique that was implemented on a contact mask aligner. The approach is based on monitoring the diffraction signal of a beam that is transmitted through gratings on the substrate and those on the mask as they are translated with respect to one another during pre-exposure alignment. The homogeneous layers are fabricated using a polymer material, SU-8, that is spin-coated and then planarized during its curing process.

The notched filtering characteristics of stratified volume holographic grating

Utilizing the tool of beam propagation method (BPM) to calculate the zeroth order diffraction beam intensity, we find SVHG displays notched diffraction response as a function of the readout wavelength. Using the method of SA and considering the variance of refractive index as the readout wavelength changes, a practiced notch filter can be designed and the period of the filter is discussed.

Stratified volume diffractive optical elements as high-efficiency gratings

We propose stratified volume diffractive optical elements as a new type of diffractive optical element that is capable of functioning as a high-efficiency grating in applications with requirements not suited to traditional holographic or diffractive optical techniques. In this approach, diffractive optical fabrication methods are used to construct an optical structure that emulates volume grating behavior. We discuss the diffraction properties of stratified volume diffractive optical elements and compare them with those used previously in both volume holographic optical elements and stratified volume holographic optical elements. A systematic design process is then presented for deriving structure parameters. We illustrate this process by designing a prototype stratified volume diffractive optical element to meet the operational specifications for a beam-scanning element in a spaceborne coherent wind lidar. We use numerical simulation to assess the performance of the prototype element, including sensitivity to fabrication errors.

Electric-field-switchable stratified volume holograms in photorefractive polymers

Two- and four-layer stratified volume holograms have been fabricated from the photorefractive polymeric material poly(methyl methacrylate): (1,3-dimethyl-2,2-tetramethylene-5-nitrobenzimidazoline):C(60) and characterized by holographic four-wave mixing experiments. Coherent addition of diffracted fields from the individual layers is observed, leading to a diffraction efficiency that increases with the square of the active layer thickness. Electricfield switching of the diffraction efficiencies of individual layers is demonstrated. The angular selectivity of the diffraction efficiency is also characterized for one, two, and four active layers. The angular width of the peaks narrows with increasing total structure thickness in agreement with theory.

Analysis of photorefractive stratified volume holographic optical elements

An analytical model is developed to study layered structures of photorefractive thin films, a promising application of stratified volume holographic optical elements. The theory gives a closed-form solution for the first-order diffraction efficiency of such elements. A new holographic multiplexing scheme that uses the photorefractive phase shift induced by an applied electric field is also analyzed with this theory.

Multiple beam generation using a stratified volume holographic grating

The parameters of several stratified volume holographic gratings are optimized in order to obtain high diffraction efficiency beam spliters. Two-, three-, five-, seven-, and nine-beam fan-outs are theoretically studied and compared with what has been achieved by other means. With a simple optical setup, a fan-out element that generates seven beams of equal intensity is experimentally realized and a comparison with theory is made.

Diffraction properties of stratified volume holographic optical elements

We present a unified treatment of the diffraction properties of stratified volume holographic optical elements (SVHOE’s). We show that the relative phasing of the diffraction orders as they propagate from layer to layer gives rise to a unique notched diffraction response of the +1 order (for the case of Bragg incidence) as a function of the normalized buffer-layer thickness, the grating spatial frequency, and the readout wavelength. For certain combinations of these parameters Bragg diffraction behavior characteristic of volume holographic optical elements (VHOE’s) is observed, whereas for other combinations pure Raman–Nath behavior periodically recurs. By using these same relative-phasing arguments, the principal features of the periodic angular sensitivity of the +1 and −1 orders can be predicted. In addition to examining the fundamental aspects of SVHOE diffraction behavior, we discuss several possible applications, including optical array generation, spatial frequency filtering, and wavelength notch filtering. With the use of the SVHOE concept, holographic materials with otherwise exemplary characteristics that are currently available only in thin-film form can be used in structures designed either to access unique SVHOE diffraction properties or to emulate conventional VHOE’s.