Perfect Phase Research Articles

Exchange-correlation functional's impact on structural, electronic, and optical properties of (N2H5)PbI3 perovskite

One of the most popular multifunctional materials in optoelectronic research domains is organometallic perovskites. In this research, DFT calculation on Hydrazinium Lead Iodide (N2H5PbI3, HAPI) perovskite with orthorhombic phase has been studied with distinct exchange-correlation functionals. HAPI showed a slight structural deformation using the LDA CAPZ functionals, revealing the minimum total energy. A very slight change in Mulliken and Hirshfeld charges of each element was observed due to the variation of functionals. The GGA calculations resulted in a perfect orthorhombic phase of HAPI, whereas LDA functional showed slight deformation from the orthorhombic phase. The band gaps of 1.644, 1.633, 1.618, and 1.650eV were obtained using GGA (PBE, PBEsol, PW91) and LDA (CAPZ) functionals, respectively. HAPI showed a high absorption coefficient of 104cm-1 order with strong absorption of high energy visible wavelength. A maximum refractive index of 2.8 was observed in the visible wavelength region and a high optical conductivity of over 1015 s-1 suggests that HAPI can be a potential material for numerous optoelectronic research.

Mid-infrared difference-frequency generation in AlGaAs-on-insulator waveguides

A design study is presented for difference-frequency generation (DFG) to the mid-infrared (MIR) at 2.3 µm in AlGaAs waveguides heterogeneously integrated on silicon. Perfect phase matching (PhM) is achieved in simulations by engineering the dimensions of the waveguide and by tuning the wavelengths of the input sources. An optimal design of the waveguide is found with a width of 1196 nm and height of 146 nm with a length of about 5 mm. We expect a signal output power of about 1 mW at 2389 nm and a wavelength range from 2231 to 2574 nm by the use of tunable sources around 940 and 1550 nm. The tolerance of the input wavelengths and waveguide dimensions required for perfect PhM is also estimated showing the feasibility of the fabrication. This offers a promising design for a compact MIR source on a chip to be used for gas sensing, in particular for carbon monoxide and ammonia, and for DFG of single photons to the C-band.

Intelligent Reflecting Surface-Aided Downlink SCMA

Recently, intelligent reflecting surfaces (IRSs) and nonorthogonal multiple-access (NOMA) have emerged as energy and spectrally efficient techniques for next-generation wireless networks. Thus, in this article, IRS-aided downlink sparse code multiple access (SCMA) system is analyzed for the next-generation wireless networks. In the proposed IRS-aided SCMA (IRS-SCMA), the base station (BS) communicates with single-antenna users with the help of an IRS. The impact of different phase shift methods at the IRS panel is studied in the IRS-SCMA, and observed that the average phase shift method has a very close performance to the perfect phase shift (optimal) with low complexity. We analyze symbol error rate and sum-rate performance of the IRS-SCMA. Simulation results show that the proposed IRS-SCMA outperforms the corresponding IRS-aided power domain nonorthogonal multiple access (PD-NOMA), and SCMA without IRS schemes. Further, the impacts of various system's parameters, such as the number of IRS reflecting elements, channel fading, SCMA codebooks, IRS location, and the number of users on the system performance are studied.

High FOM Refractive Index Sensor Based on Quasi-Bound States in the Continuum of Tri-Prism Metasurface

Due to the inevitable ohmic losses and radiation losses from metal materials and nanoparticles, the figure of merit (FOM) of plasmon sensors is usually very low. The all-medium material combined with bound states in the continuum (BIC) can effectively improve the FOM of sensors. In this article, a single-layer tri-prism metasurface sensor based on quasi-BIC (Q-BIC) was first proposed and simulated. Some meaningful results were obtained by adjusting and optimizing the structural parameters. By reducing duty ratio (DR) and dielectric column height, the sensor was sensitive to refractive index (RI) changes and had an excellent spectral performance. The results showed the sensitivity and full width at half maximum (FWHM) of the single-layer tri-prism sensors were 680.7 nm/RIU and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\times 10^{-{2}}$ </tex-math></inline-formula> nm, respectively, and the FOM could reach <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.36\times 10^{{4}}$ </tex-math></inline-formula> RIU−1. On this basis, we proposed a novel double-layer metasurface sensor model to improve the sensing performance and simulate it further. Because of the complete symmetry of the two-layer metasurfaces, the sensor had perfect phase matching condition. Under the same conditions, double-layer sensor had higher sensitivity and narrower FWHM in Q-BIC. The results showed the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> and FWHM of the sensor were 715.6 nm/RIU and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7\times 10^{-{5}}$ </tex-math></inline-formula> nm, respectively, and the FOM could reach <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{{7}}$ </tex-math></inline-formula> RIU−1, detection limit (DL) could reach <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.89\times 10^{-{9}}$ </tex-math></inline-formula> RIU. FOM had been improved by three orders of magnitude than the single-layer sensor. It provided ideas for sensors with ultralow DLs in the future.

Helical particle manipulation based on power-exponent-phase acoustic vortices generated by a sector transducer array

The characteristics of traditional acoustic vortices (AVs) were verified by the cross-sectional axisymmetric pressure distributions with perfect phase spirals around the center pressure null. In order to generate a non-axisymmetric pressure distribution, the concept of power-exponent-phase was first introduced into the formation of AV beams, named “power-exponent-phase acoustic vortices (PAVs)” in this paper. Based on a ring-array of sector transducers, the helical distribution of the low-pressure valley in cross-sections of PAVs, which enables particles to move from a distant position to the center low-potential well along a certain spiral passageway, was proved theoretically. The particle manipulation behavior for PAVs with a power order of 2 is numerically modeled and experimentally confirmed. The results show that PAVs with a non-axisymmetric spiral pressure distribution can be used to realize the directional transport of particles in an enlarged scope, suggesting prospective application potential in biomedical engineering.

Transformative resilience: Transformation, resilience and capacity of coastal communities in facing disasters in two Indonesian villages

This study aims to identify the transformation process of coastal village communities in building resilience to disasters. We develop our theoretical framework based on the concepts of socio-ecological resilience, transformative resilience, panarchy systems and resilience capacities. Using the qualitative research methods, we examine two cases of coastal villages in Indonesia that represent differing levels of socio-economic vulnerability and community responses to disasters. The findings of this study highlight that the building of transformative resilience is affected by the transformation phases, the heterogeneity and interdependence of capacities, and the intensity of resources used as capacity. The building process of transformative resilience cannot happen instantly but requires an ideal timeframe for transitional phase navigation in which communities form valley and peak waves to create a perfect phase in each regime. This condition triggers the achievement of high resilience conditions in the face of disasters. Although endogenous capacities, in the form of local social networks and agents of change, have become the key aspects of resilience, openness to external conditions and collaborations are also essential in nurturing transformation. Our findings suggest an important implication for policy, in that a long-term transformation process should be taken into account in policymaking. Further, in enhancing the resilience of coastal communities it is important to build their innovative capacities, among other things, by nurturing their networks through various opportunities and exposures to external parties which enable collaborations and exchanges of knowledge.

First principles investigations of structural and electronic properties of Ga-doped ZnZrOx solid solutions for catalytic reduction of CO2

ZnZrOx and gallium-doped ZnZrOx solid solutions exhibit excellent catalytic properties for the hydronation of CO2 to methanol. However, the details of the structures and catalytic properties are not fully understood. Herein, density functional theory has been used to explore the structural, electronic and catalytic properties of ZnZrOx and gallium-doped ZnZrOx catalysts. We used zinc-doped Zr sites of tetragonal ZrO2 with different Zn concentrations as a model to simulate the ZnZrOx solid solution. For the Ga-doped ZnZrOx catalysts, Zr atoms were substituted by Ga atoms. The doping of Zn atoms in ZrO2 reduce the coordination numbers of Zr atoms. Heavily Zn-doped ZrO2 systems do not maintain the tetragonal structure and, hence, deviate from the perfect tetragonal phase. At ∼29.16% Zn concentration, the bandgap of ZnZrOx has been reduced from 4.45 to 2.45 eV. The insertion of Ga in ZnZrOx solid solutions shifts the conduction band edges back, increasing the bandgap of the solid solutions. The Ga doping improves the CO2 adsorption ability of ZnZrOx solid solutions and efficiently dissociates the H2 molecules. On the surface of Ga-Zn doped ZrO2(101), the hydrogenation of CO2 to methanol via the formate pathway is more favorable than the CO pathway.

General solution of phase mismatched second harmonic conversion efficiency in periodically poled nonlinear medium

In this work we provide for the first time a novel and more accurate second harmonic generation (SHG) conversion efficiency equation for periodically poled nonlinear medium. We believe the equation derived in this work is more useful than equations reported in previous works which are limited because it is considering the case of either nondepleted pump regime or perfect phase matching. The equation derived in this work tackles the general case: depleted pump regime and phase mismatching which makes it important for theoretical – experimental study. We used MgO:PPLN crystal as an example to illustrate SHG conversion efficiency as function of crystal length, laser power density, crystal temperature and beam divergence. We included fundamental and second harmonic waves reflection at entrance and exit surfaces respectively and performed numerical solution using fifth-order Runge-Kutta method. The numerical results show excellent match with analytical results obtained from the derived formula. We compared our theoretical results with experimental results reported in the literature and the comparison shows a good match. Finally, we performed a comparison between depleted and nondepleted pump regime. The results show a difference of 20% between two efficiencies making nondepleted efficiency equation, which used in many theoretical – experimental comparisons, not accurate at high power densities.

Does perfect filtering really guarantee perfect phase correction for diffusion MRI data?

Owing to its merit of avoiding noise-floor, phase correction is recently used to reconstruct real-valued diffusion MRI data by employing an image filter to estimate the noise-free background phase. However, several studies report an unexpected signal-loss issue for their reconstruction results, with its causing reason still remaining unclear. Although phase correction has achieved promising results in mitigating the signal-loss issue via improving the employed image filter, we have observed counterintuitive results that an advanced filter generates severe artifacts in our previous work. Considering the potential issues with phase correction procedures, in this paper, we argue that even a perfect image filter is insufficient to produce perfect phase correction. To point out the reason why phase correction introduces signal-loss and address this issue, we first propose a complex polar coordinate system (CPCS) to analyze its procedures in detail; second, based on CPCS, we find that phase correction has not sufficiently utilized the background phase, and thus propose a quantitative criterion to fully exploit the background phase; eventually, we propose a phase calibration procedure to remedy current phase correction. Extensive experimental results, including those on synthetic and real diffusion MRI data, demonstrate that our proposed method significantly reduces signal-loss and also eliminates artifacts in FA maps, particularly with improved accuracy on FA.

Perfect absorption and phase singularities induced by surface lattice resonances for plasmonic nanoparticle array on a metallic film.

The formation of pairs of perfect absorption associated with phase singularities in the parameter space using the hybridized structure constructed with a metallic nanoparticle array and a metallic film is promising to enhance light-mater interactions. However, the localized plasmon resonances of the array possess strong radiative losses, which is an obstacle to improve the performances for many applications. On the contrary with the subwavelength array hybridized structure, this study shows that by enlarging the lattice spacing, the oscillator strength of the nanoparticles can be enhanced with the formation of surface lattice resonance, thereby leading to similar but much narrower pairs of perfect absorption due to the interactions with the Fabry-Pérot cavity modes. Furthermore, when the surface plasmon polariton mode shift to the same spectral range associated with the enlarged lattice spacing, the coupling and mode hybridization with the surface lattice resonance result in an anticrossing in the spectra. Although the resonance coupling does not enter the strong coupling regime, the quality factors (∼ 134) and near-field enhancements (∼ 44) are strongly enhanced for the hybridized resonance modes due to the effectively suppressed radiative losses compared with that of the localized plasmon resonances, which make the hybridized structure useful for the design of functional nanophotonic device such as biosensing, multi-model nanolasing, and high-quality imaging.

Passive Quantum Phase Gate for Photons Based on Three Level Emitters.

We present a fully passive method for implementing a quantum phase gate between two photons traveling in a one-dimensional waveguide. The gate is based on chirally coupled emitters in a three level V configuration, which only interact through the photon field without any external control fields. We describe the (non)linear scattering of the emerging polariton states and show that for near resonant photons the scattering dynamics directly implements a perfect control phase gate between the incoming photons in the limit of many emitters. For a finite number of emitters we show that the dominant error mechanism can be suppressed by a simple frequency filter at the cost of a minor reduction in the success probability. We verify the results via comparison with exact scattering matrix theory and show that the fidelity can reach values F∼99% with a gate success probability of >99% for as few as eight emitters.

"번역문에 나타난 한·일 상표지 대응 양상 연구 -완료 국면에서 ‘-어 있는’과 ‘-은’의 시점을 중심으로- -완료 국면에서 ‘-어 있는’과 ‘-은’의 시점을 중심으로-"

This study aims to investigate the relationship between perspectives and aspects, assuming that differences in the perspective of two languages lead to differences in the choice of aspect markers. When the two situations form a complex sentence at different intervals of time, this study focuses on the perspective of the subject of conception, in relation to expressing it with ‘-eo iss-neon’ in Korean literary works and ‘-ta’ in Japanese translations. The choice of aspect marker changes depending on where the perspective of the subject of conception is during the Perfect phase. The Korean perspective is ‘object viewed’, and the two situations are recognized as coexisting within one fixed frame. The Japanese perspective, by means of the ‘vantage point’, recognized the temporal order of the two situations in sequence.

Analytical Method Validation for Simultaneous Estimation of Domperidone and Omeprazole by RP-HPLC Method

The developed RP-HPLC technique lets in speedy and particular omeprazole and domperidone determinations, the goal of the current painting is to improve and extend the chromatographic circumstances, to broaden RP-HPLC method. a variety of mobility phases were tested for the duration of technique improvement, some of the numerous cell phases methanol, acetonitrile and phosphate buffer changed into discovered to be a perfect cell phase, because it provided optimal peak forms and high resolution. The go with the flow rate changed into optimized at 0.90 mL/min. The development of the isocratic elution method for omeprazole and domperidone made it perfect for quick and routine analysis. Omeprazole and domperidone linearity and correlation coefficient had been located to be 10 to 50 ug/mL 0.997, and 0.998, respectively. The restriction of detection for omeprazole and domperidone turned into discovered to be 1.78 and 3.15 and the limit of quantification changed into observed to be 544 and 956. With the assay procedure, the methodology has been recognized as accurate. The %assay become determined to be 98 and 73. The evolved technique changed into confirmed to an excellent accuracy and precision. The isocratic elution approach evolved for the dedication of omeprazole and domperidone perfectly suited for rapid and ordinary evaluation. This technique shows that right reproducibility of the effects. moreover this approach become easy, touchy, and accurate. Degradation studies had been accomplished, right here the drug stability outcomes have been within the variety of acceptance standards 85 to 115%. Moreover, this approach was easy, touchy, and correct.

Wideband Collinear Phase Matching in Cubic Semiconductors via the Linear Electro-Optic Effect: A Theoretical Study

In order to achieve collinear phase-matched nonlinear optical frequency conversion in cubic crystals, a novel method to induce and modulate the birefringence based on the linear electro-optic effect was studied. Taking terahertz generation with ZnTe and CdTe crystals of the 4¯3m point group as an example, an external electric field provided the freedom to realize perfect phase matching (PM) in a wide bandwidth up to 2 THz for difference frequency generation, with monochromatic optical waves at around 800 nm and 1010 nm, respectively. Theoretical simulations showed that such a method helps to extend the terahertz frequency, enhance the conversion efficiency, and alleviate the limitation on the pump wavelength, which is highly favorable for nonlinear optical uses of cubic crystals. Simultaneous wideband terahertz generation pumped by ultrashort laser pulses via optical rectification or difference frequency mixing was also discussed, indicating that an electric field can be used to modulate the PM characteristics without changing the group velocity-matching condition. Tuning the nonlinear interaction by an applied voltage is fast, robust, and convenient compared to other approaches. In addition, the linear electro-optic effect can make the nonlinear crystal a compact and high-speed terahertz amplitude modulator, which has great potential in radar, communication, imaging, etc.

Thin film lithium niobate electric field sensors.

We present our results for using thin film lithium niobate devices for electric field sensing applications. Micro-ring modulator and Mach-Zehnder modulator-based electric field sensors are demonstrated. Micro-ring resonator sensors can be used for low frequency (up to several GHz) electric field sensing applications and achieve a high sensitivity of 80 mV/(m Hz1/2) with a very compact size of 300μm, as limited by the intensity and phase noise of the used distributed feedback laser. A measurement bandwidth of 2.5GHz is measured for these sensors and is limited by the detector bandwidth. Alternatively, Mach-Zehnder modulators allow for perfect phase matching between the radio frequency signals and optical signals, and they can be used for electric field sensing up to several THz. A sensitivity of 2.2 V/(m Hz1/2) was obtained using our Mach-Zehnder electric field sensor with an interaction length of 600μm. The Mach-Zehnder sensor can sense electric fields with frequencies reaching 0.6THz based on the calculated results.

Analysis of the Low Cycle Fatigue Behavior of DP980 Steel Gas Metal Arc Welded Joints

Dual phase (DP) steels have high strength, while maintaining outstanding elongation capacities. This is possible using a well-controlled thermomechanical process that produces a perfect phase combination in the DP microstructures. However, automotive makers are required to weld the DP steels, which generates a soft zone in the microstructure. In this work, 1.6 mm-thick DP980 steel sheets were welded by gas metal arc welding process to analyze the response of the welded soft zone to cyclic loading conditions. Conducted macrographic and metallography analyses revealed good quality in the appearance of the welded joints, with a complete fusion of the DP980 joint and without the presence of discontinuities. Low cycle fatigue tests of the DP welded joints were conducted under a constant amplitude strain control mode. The welded joints experienced a fatigue life reduction with respect to the DP980 steel of ~16% at strain amplitudes of 0.2, 0.3, and 0.4%. For strain amplitudes larger than 0.6%, the fatigue life of the welded joint was reduced by 39%. Weld thermal cycles combined with metallography analysis indicated that a tempered process of the martensite during the welding was responsible for the soft-zone formation and the poor fatigue response.

Coherent Multiantenna Receiver for BPSK-Modulated Ambient Backscatter Tags

Ambient backscatter communication (AmBC) is an emerging communication technology enabling green Internet of Things deployments. The widespread acceptance of this paradigm is limited by the low signal-to-interference-plus-noise ratio (SINR) of the signal impinging on the receiver antenna due to the strong direct path interference and unknown ambient signal. The adverse impact of these two factors can be mitigated by using noncoherent multiantenna receivers, which are known to require a higher SINR to reach the bit-error-rate (BER) performance of coherent receivers. However, considering the unknown ambient signal, unknown location of AmBC tags, and varying channel conditions, coherent receivers for AmBC systems are rarely studied in the literature. In this article, a coherent multiantenna receiver, which requires no prior information of the ambient signal for decoding the binary-phase-shift-keying (BPSK) modulated signal, is presented. The performance of the proposed receiver is compared with an ideal coherent receiver that has perfect phase information, and also with the performance of a noncoherent receiver, which assumes distributions for ambient signal and phase offset caused by the excess length of the backscatter path. Comparative simulation results show the designed receiver can achieve the same BER performance of the ideal coherent receiver with 1-dB more SINR, which corresponds to 5-dB or more gain with respect to noncoherent reception of on-off-keying modulated signals. Variation in the detection performance with the tag location shows that the coverage area is in the close vicinity of the transmitter and a larger region around the receiver, which is consistent with the theoretical results.

Location Sensing and Beamforming Design for IRS-Enabled Multi-User ISAC Systems

This paper explores the potential of the intelligent reflecting surface (IRS) in realizing multi-user concurrent communication and localization, using the same time-frequency resources. Specifically, we propose an IRS-enabled multi-user integrated sensing and communication (ISAC) framework, where a distributed semi-passive IRS assists the uplink data transmission from multiple users to the base station (BS) and conducts multi-user localization, simultaneously. We first design an ISAC transmission protocol, where the whole transmission period consists of two periods, i.e., the ISAC period for simultaneous uplink communication and multi-user localization, and the pure communication (PC) period for only uplink data transmission. For the ISAC period, we propose a multi-user location sensing algorithm, which utilizes the uplink communication signals unknown to the IRS, thus removing the requirement of dedicated positioning reference signals in conventional location sensing methods. Based on the sensed users' locations, we propose two novel beamforming algorithms for the ISAC period and PC period, respectively, which can work with discrete phase shifts and require no channel state information (CSI) acquisition. Numerical results show that the proposed multi-user location sensing algorithm can achieve up to millimeter-level positioning accuracy, indicating the advantage of the IRS-enabled ISAC framework. Moreover, the proposed beamforming algorithms with sensed location information and discrete phase shifts can achieve comparable performance to the benchmark considering perfect CSI acquisition and continuous phase shifts, demonstrating how the location information can ensure the communication performance.

Nanostructured Strontium Titanate Perovskite Hyperbolic Metamaterial Supported Tunable Broadband THz Brewster Modulator

The investigation was made of nanostructured intensity and phase modulators, the designs of which are based on Brewster angle manipulation. The configuration consists of thin indium tin oxide, strontium titanate and quartz layers embedded on silicon substrate. The structure exhibits elliptical and hyperbolic metamaterial kinds, which can be manipulated by varying the ambient temperature. The design yields broadband intensity and phase modulator with 99.8% modulation depth and perfect phase shift (i.e., 180°), respectively, at the room temperature. This would find potentials in active polarization switches, modulators and tunable phase shifters operating in the THz regime.

Optical Harmonic Generation in 2D Materials

Abstract2D materials are emerging as ideal candidates for fundamental investigations and new technologies due to their unique optoelectronic properties. Giant nonlinear susceptibility and perfect phase matching in 2D materials lead to extraordinary nonlinear light matter interactions, thus enabling several potential applications and fundamental scientific discoveries in nonlinear optics. For instance, second harmonic generation in 2D materials play an important role in optical devices such as, lasers, tunable waveguides, electro‐optic modulators, and switches. This review will discuss optical harmonic generation (OHG) processes, various characterization modes, and tuning techniques in 2D materials. The future prospectives for OHG in 2D materials is discussed. The extremely promising attributes of combining nonlinear optics and 2D materials is becoming a highly important multidisciplinary field.