Anomalous Polarization Pattern Evolution of Raman Modes in Few-layer ReS2 by Angle-resolved Polarized Raman Spectroscopy

Low-symmetry of ReS2 has not only in-plane but also out-of-plane anisotropic light scattering, which is complicated, yet interesting with intrinsic strong electron-phonon coupling. In such case, the Raman tensor also...

Mueller Matrix Polarimetry with Invariant Polarization Pattern Beams

A wide class of nonuniformly totally polarized beams that preserve their transverse polarization pattern during paraxial propagation was studied. Beams of this type are of interest, in particular, in polarimetric techniques that use a single input beam for the determination of the Mueller matrix of a homogeneous sample. In these cases, in fact, it is possible to test the sample response to several polarization states at once. The propagation invariance of the transverse polarization pattern is an interesting feature for beams used in these techniques, because the polarization state of the output beam can be detected at any transverse plane after the sample, without the use of any imaging/magnifying optical system. Furthermore, exploiting the great variety of the beams of this class, the ones that better fit specific experimental constrains can be chosen. In particular, the class also includes beams that present all possible polarization states across their transverse section (the full Poincaré beams (FPB)). The use of the latter has recently been proposed to increase the accuracy of the recovered Mueller matrix elements. Examples of FPBs with propagation-invariant polarization profiles and its use in polarimetry are discussed in detail. The requirement of invariance of the polarization pattern can be limited to the propagation in the far field. In such a case, less restrictive conditions are derived, and a wider class of beams is found.

International configuration in the post-Covid 19 era from constructivism’s perspective view

The global outbreak of Covid-19 pneumonia in 2020 has instantly changed the appearance of the world and caused a sudden change in the interaction pattern of international actors. Actors at all levels have survived the current situation for more than a year under the premise of being forced to change. However, actors at all levels who are unwilling to succumb to the impact of the current epidemic are aiming to restore their pre-epidemic lifestyles, and are drawing up plans to rebuild the international order and respond to new challenges, including the current vaccine policies of various countries-how to respond appropriately demands on a global scale. Therefore, all past political and democratic issues have been repositioned in the post-epidemic era of environmental changes to be verified again. Most members of the international community have strengthened multilateralism in their cooperation in the fight against the epidemic. However, the Trump administration's “America First” and unilateralism pose the greatest challenge to the international multi-polarization pattern and a fair and reasonable world order. Therefore, analyzing and studying changes in the international pattern and world order under the epidemic will help improve practice and theoretical consciousness, and promote the construction of contemporary new international relations and a community with a shared future for mankind. This article attempts to analyze the international configuration in the post-Covid 19 era from the perspective of Windt's constructivism.

How Dung Beetles Steer Straight

Distant and predictable features in the environment make ideal compass cues to allow movement along a straight path. Ball-rolling dung beetles use a wide range of different signals in the day or night sky to steer themselves along a fixed bearing. These include the sun, the Milky Way, and the polarization pattern generated by the moon. Almost two decades of research into these remarkable creatures have shown that the dung beetle's compass is flexible and readily adapts to the cues available in its current surroundings. In the morning and afternoon, dung beetles use the sun to orient, but at midday, they prefer to use the wind, and at night or in a forest, they rely primarily on polarized skylight to maintain straight paths. We are just starting to understand the neuronal substrate underlying the dung beetle's compass and the mystery of why these beetles start each journey with a dance.

Propagation features of a class of beams radiated from pseudo-Schell model vectorial sources

Pseudo Schell-model sources were introduced and studied in the scalar domain as those partially coherent sources that present a degree of coherence depending on the difference between the radial coordinates of the two considered points. In this work we study the propagation features of a class of beams radiated from sources of this kind, but endowed with a vectorial nature. The polarization pattern and the degree of polarization are not uniform across the beam section but remain invariant upon free paraxial propagation. On the other hand, their coherence and irradiance features are also non-uniform but in this case they change at each z-plane. The field characteristics can be varied on acting on the free parameters of the cross-spectral density matrix of the source.

Compact Circularly Polarized Slotted Symmetric V slits Microstrip Patch Antenna for ISM Band Applications

This paper presents a short microstrip patch antenna and analyzes its characteristics in simulation and measured ways. The proposed antenna is meant to be used from 2.4 to 2.5 GHz at the resonant frequency of 2.45 GHz Industrial, Science, and Medical (ISM) spectrum. Besides, insert a diagonal slot in the main patch, and two cutting edges with V-slit gives the antenna to propagate a circular polarization pattern. The paper aims to start learning a simple C.P. patch antenna supported the basic concept of microstrip antenna theory. A single-feed C.P., truncated corners, and slit and slot methods are employed to model the antenna apart from its parametric study. The substrate material of the developed antenna is FR-4, and it's a relative permittivity of 4.4. The antenna incorporates a compact overall size of 0.389λ0 × 0.389λ0 × 0.013λ0, where λ0 is that the corresponding free-space wavelength at 2.45 GHz. FEKO has been used for not only designing the antenna model but also analyzing its performances. Simulated and measured results have reported that the antenna can work in ISM bands (2.42-2.5 GHz) with VSWR< 2, low realized gain, and the limited 3-dB axial ratio at 2.45 GHz.

Turbid Underwater Polarization Patterns Considering Multiple Mie Scattering of Suspended Particles

It is still unclear how water turbidity affects the underwater polarization pattern. Current simulations only consider single Rayleigh scattering of water molecules and ignore multiple Mie scattering of suspended particles. In this study, a method based on a combination of Monte Carlo numerical simulation and Mie scattering theory is used to establish a model of the turbid underwater polarization distribution. Stokes vector and Mueller matrix are used to simulate the underwater polarization patterns within Snell's window. The distribution patterns and dynamic changes of the simulation are consistent with field measurements. The maximum depth that the polarization pattern can be maintained is calculated for different water types. The influence of water turbidity on polarization patterns is discussed. This model provides a tool for researchers to quantitatively analyze the distribution of turbid underwater polarization. In addition, the study is valuable for remote sensing and marine surveillance.