Analysis Of Angular Dispersion Research Articles

Excitation of optical tamm state for photonic spin hall enhancement

This work presents a dielectric material-based optical Tamm state (OTS) excitation technique with modified dispersion characteristics for photonic spin hall effect (PSHE) enhancement. The dispersion analysis of the structure is carried out to validate OTS’s localization and corresponding PSHE generation for a given polarization at 632.8 nm incident wavelength. The exceptional points are optimized by considering thickness-dependent angular dispersion analysis. PSHE-based transverse displacement (PSHE-TD) is dependent on the defect layer thickness. The optimized structure provides 10.73 times lambda (or 6.78 upmum) PSHE-TD at an incidence angle of 41.86{}^{circ }. The PSHE-TD of the optimized structure is sufficiently high due to the much narrower resonance than the plasmonic-based structures. Further, the structure’s potential to function as a PSHE-TD-based optical sensor is assessed. The optimized structure shows an analytical average sensitivity of about 43,789 upmum/RIU showing its capability to detect the analytes with refractive index variations in the 10^{-4} range. The structure demonstrates a three-time sensitivity improvement compared to similar resonance designs. Considering only dielectric materials in the proposed structure and considerably enhanced PSHE-TD, the development of highly efficient PSHE-TD-assisted commercial structures is anticipated.

Nanophotonic resonator assisted photonic spin Hall enhancement for sensing application

This manuscript presents a dielectric resonator structure with altered dispersion characteristics to enhance the photonic spin Hall effect (PSHE). The structural parameters are optimized to enhance the PSHE at 632.8 nm operating wavelength. The thickness-dependent angular dispersion analysis is carried out to optimize the structure and obtain the exceptional points. The PSHE-induced spin splitting shows a high sensitivity to the optical thickness of the defect layer. This gives a maximum PSHE-based transverse displacement (PSHE-TD) of around 56.66 times the operating wavelength at an incidence angle of 61.68°. Moreover, the structure’s capability as a PSHE-based refractive index sensor is also evaluated. The analytical results demonstrate an average sensitivity of around 33,720 μm/RIU. The structure exhibits around five times higher PSHE-TD and approximately 150% improvement in sensitivity than the recently reported values in lossy mode resonance structures. Due to the purely dielectric material-assisted PhC resonator configurations and significantly higher PSHE-TD, the development of low-cost PSHE-based devices for commercial applications is envisaged.

Analysis of angular dispersion induced by wavefront rotation in nanosecond optical parametric chirped pulse amplification.

Angular dispersion observed in a nanosecond optical parametric chirped-pulse amplification (ns-OPCPA) amplifier adopted in the frontend of a multi-PW laser was analyzed. The theory on the angular dispersion, extended by including the wavefront rotation and the pulse front tilt of a strongly chirped laser pulse, revealed that the wavefront rotation is a major contributor to the angular dispersion, as compared to the pulse front tilt, in a ns-OPCPA amplifier. It was also shown that the wavefront rotation could be introduced by the phase mismatch and the noncollinear propagation angle in the noncollinear ns-OPCPA amplifier. The theoretical prediction was experimentally verified by measuring the angular dispersion of the ns-OPCPA frontend installed in the 20-fs, 4-PW Ti:Sapphire laser. We emphasize the importance of the proper characterization and control of the angular dispersion in the ns-OPCPA amplifier since the focus intensity of an ultrahigh power laser could be significantly reduced due to the spatiotemporal effect even for small induced angular dispersion.

Demystifying the pH dependent conformational changes of human heparanase pertaining to structure-function relationships: an in silico approach.

Heparanase (HPSE) is an endo-β-D-glucuronidase that has diverse functions in mammals which includes cell survival, cell adhesion and cell migration. HPSE features both enzymatic and non-enzymatic functionalities in a pH dependent manner. Hence, in this study, an extensive molecular dynamics simulation, molecular docking, protein Angular dispersion analysis were performed for apo form and holo forms to understand its conformational changes at varied pH conditions. On comparative conformational analysis of apo and holo forms, it was inferred that the HSPE has undergone pH dependent structural changes, thereby affecting the binding of Heparan sulfate proteoglycan (HSPG). Moreover, HPSE also showed favourable structural changes for optimal binding of HSPG at pH 5.0 and 6.0, as inferred from functional flap displacements within HPSE. Thus, this study provides significant insights on optimal pH for HPSE to exhibit its enzymatic activity. The outcome of this study shall aid in ideal lead generation for targeting HPSE mediated disease conditions.

Optofluidic distributed feedback lasers with evanescent pumping: Reduced threshold and angular dispersion analysis

We demonstrate an evanescently pumped water-based optofluidic distributed feedback (DFB) laser with a record low pump threshold of ETH=520 nJ. The low threshold results from an optimized mode shape, which is achieved by a low refractive index substrate, and from the use of a mixed-order DFB grating. Investigating the photonic band structure via angular dispersion analysis both above and below lasing threshold allows us to measure the refractive index of the liquid gain layer and to determine the device parameters such as the waveguide core layer thickness. We show that it is possible to tailor the divergence of the lasing emission by varying the number of second order grating periods used for outcoupling.

CHARACTERIZING MAGNETIZED TURBULENCE IN M51

We use previously published high-resolution synchrotron polarization data to perform an angular dispersion analysis with the aim of charactering magnetized turbulence in M51. We first analyze three distinct regions (the center of the galaxy, and the northwest and southwest spiral arms) and can clearly discern the turbulent correlation length scale from the width of the magnetized turbulent correlation function for two regions and detect the imprint of anisotropy in the turbulence for all three. Furthermore, analyzing the galaxy as a whole allows us to determine a two-dimensional Gaussian model for the magnetized turbulence in M51. We measure the turbulent correlation scales parallel and perpendicular to the local mean magnetic field to be, respectively, delta_{para} = 98 +/- 5 pc and delta_{perp} = 54 +/- 3 pc, while the turbulent to ordered magnetic field strength ratio is found to be Bt/B0 = 1.01 +/- 0.04. These results are consistent with those of Fletcher et al. (2011), who performed a Faraday rotation dispersion analysis of the same data, and our detection of anisotropy is consistent with current magnetized turbulence theories.

Convection–diffusion derived gradient films on porous substrates and their microstructural characteristics

By virtue of the convection–diffusion effect of solution in porous solid media, an alumina substrate-supported electrolyte film (YSZ) with gradient microstructure has been successfully fabricated for the first time and structurally characterized by SEM and XRD–ADA (angular dispersion analysis). This novel fabrication technique is simple, controllable, economical and potentially applicable to fabricating electrode-supported gradient electrolyte films for SOFCs. The so-prepared YSZ-film/substrate structures are featured with a dense YSZ film of ∼10 μm, a uniform filling layer of ∼50 μm just beneath the interface and a successive diffuse layer stretching as deep as ∼250 μm within the porous substrate matrix.

Nano-Structure And Results Of Phase Transitions In The Liquid Phase Of Common Materials: Metallic And Non-Metallic Elements And Related Materials

Introduction In the following, experimental data are presented from various laboratories treating the liquid state of common elements [1–7]. The goal of this paper is not only to demonstrate that the scientific world’s picture of the structure of the liquid state is grossly oversimplified, but to suggest certain common features of the structural variability. From the mid-1960s to the mid-1980s, Vezzoli et al. employed volumetric, optical, Xray, and electrical techniques to study the discontinuous changes in the liquid state of low-melting elemental materials including sulfur, selenium, tellurium, lead, tin, bismuth and mercury. As a function of high pressure in the 1—100 kbar range, the studies included the use of Bridgman (opposed) anvil, gas cylinder, diamond cell, pistoncylinder, and hexahedral pressure transmitting systems (both quasi-hydrostatic and purehydrostatic), with various compatible external and internal heating methods. More recently, sophisticated in situ X-ray diffraction techniques have been successfully applied to the liquid phase. These involve either angular dispersion analysis, whereby a monochromatic radiation source is utilized, or energy dispersion analysis, which involves a polychromatic source. The data from both of these methods yield a characteristic scattering pattern of peaks and satellites corresponding to a preferred probabilistic shortrange liquid nanostructure [8, 9, 10]. In situ neutron diffraction studies have yielded confirming results. The data given herein provide the details of research findings on the structure of the liquid state of the elements which have been studied. For simplification, the elemental liquids that are treated herein are divided into metals and non-metals and described ad seriatim. All starting materials were 99.9999 to 99.99999% pure. Details of apparatus and measuring techniques are given in the references [1, 2].

Angular dispersion of diffraction-free optical pulses in dispersive medium

The comprehensive analysis of angular dispersion of diffraction-free optical pulsed beams in linear dispersive medium is carried out. It is shown that properties of an angular dispersion curve essentially depend on its behavior at zero point of pulse group-velocity dispersion in the medium. As an example, the angular dispersion curves in transparency region of fused silica are presented. It is demonstrated that the radius of diffraction-free pulsed beams exhibits a strong dependence on angular dispersion.

A Late Quaternary geomagnetic secular variation record from Lake Waiau, Hawaii, and the question of the Pacific nondipole low

A continuous paleomagnetic record for the last 13,000 years was obtained from the sediments of Lake Waiau, located near the summit of Mauna Kea Volcano on the island of Hawaii. The secular variation (SV) of the geomagnetic field was studied using spectral analysis and precession analysis of the magnetic vector. The hypothesis that there has been anomalously low geomagnetic SV in the central Pacific was tested using angular dispersion analysis. The inclination record has a mean value of 27° that is much lower than the 35° predicted by the geocentric axial dipole hypothesis. The spectrum obtained from spectral analysis shows major inclination peaks at periodicities of approximately 3600 and 7900 years and major declination peaks at periodicities of approximately 1100, 2000, 3300, and 7800 years. The approximately 8000‐ and 3500‐year periodicities shown in both inclination and declination spectrums may represent the dipole and nondipole variation, respectively. The approximately 1100‐ and 2000‐year periodicities are probably derived from either the sources that affect declination only or the offsets between the core sections. In addition, Bauer plots of the magnetic vector are dominated by clockwise motion. The angular dispersion calculated from lake sediments is 5.9° with respect to the mean virtual geomagnetic pole (VGP) and 9.1° with respect to the geographic pole. Both values are much lower than the 13.5° expected from paleosecular variation model G which separates the angular dispersion into components from the dipole and the quadruple families. Our results support the hypothesis that an anomalously low secular variation is a characteristic feature of the central Pacific. Furthermore, this geomagnetic behavior persists on time scales of 104 years. Regional anomalies in temperature, topography or electrical conductivity at the core‐mantle boundary are inferred to cause the low SV.