Coupling Efficiency Research Articles

Open whispering gallery mode resonators.

There are some issues with traditional whispering gallery mode (WGM) resonators such as poor light extraction and a dense mode spectrum. In this paper, we introduce a solution to these limitations by proposing open WGM (OWGM) resonators that effectively reduce the mode density and enable directional radiation through a connected waveguide at the expense of some lowering in Q-factor. Numerical simulations of two-dimensional metallic and dielectric disk resonators with holes reveal a significant increase in intermode distance. The study also extends to three-dimensional dielectric OWGM resonators, demonstrating the formation of sparse spectra suitable for photonic applications. Additionally, the design of a cylindrical Bragg microresonator connected to a single-mode fiber via an optimized topology-based connector achieves near-unity transmission and efficient coupling. This approach enhances the development of new photonic devices, addressing the limitations of traditional high Q-factor WGM resonators and offering potential advancements in laser technology and optical communications.

From In Situ Monitoring to Better Understanding of the Suzuki‐Miyaura Cross Coupling in the Solid State

AbstractEffects of various Additives, Base, Catalyst, as well as substrates on the mechanochemically‐induced Suzuki‐Miyaura reaction have been studied. In situ Raman monitoring of the solid‐state reactions gave a detailed view of the reaction course and allowed a direct comparison of the time‐resolved product formation. The acquired knowledge allows in‐depth understanding of the reaction, especially the action of the catalyst in presence of diverse chemicals, leading to the more efficient cross coupling reactions in the solid state.

Efficient TE-polarized mode coupling between a plasmonic tunnel junction and a photonic waveguide

Efficient TE-polarized mode coupling between a plasmonic tunnel junction and a photonic waveguide

Synthesis of Indole- and Benzofuran-Based Benzylic Sulfones by Palladium-Catalyzed Sulfonylation of ortho-Iodoaryl Allenes.

A highly efficient palladium-catalyzed domino coupling reaction of ortho-iodoaryl allene with sodium sulfonates under mild conditions is described. This novel method provides a practical protocol to access diverse indole- and benzofuran-containing sulfones by simultaneous construction of C(sp2)-C(sp2) bond and a C(sp3)-S bonds in one pot. The salient features of this transformation include simple operations, broad substrate scope, and good functional group tolerance.

Misalignment analysis of WPT level 3/Z2-class of CirPT with DDPR and CirPR for EVs stationary charging.

Future inductive charging ports must possess the capability to charge any electric vehicle (EV), irrespective of the specific coil architecture it is equipped with. This study examines the misalignment scenarios of the global circular pad at transmitter side (CirPT) with circular receiver pad (CirPR) and a double-D receiver pad (DDPR). The CirPT, CirPR, and DDPR configurations for WPT3 (11.1kW) with ground clearance meeting the Z2-class specifications and above ground surface installation are built by utilizing circuit analysis and 3D-finite element simulations, as outlined by the Society of Automotive Engineering (SAE) J2954 standard. The simulated designs are employed to determine the frequency (f) and the compensating network components (CNCs) required to achieve optimal power transfer efficiency while maintaining nominal power levels. The analysis of misalignment scenarios involves examining various performance factors, including coupling coefficient (k), transmission power (Po), efficiency (η), and leakage electromagnetic fields (EMFs). These factors are assessed under conditions of ideal alignment, as well as various linear and angular misalignments within the inductive charging system. The results demonstrate that both the CirPR and DDPR configurations can successfully interface with the CirPT to provide the required Po to the EV battery with commendable efficiency. In perfect alignment, the efficiencies are 95.10% for the CirPT-CirPR model and 91.60% for the CirPT-DDPR model. In maximum misalignment, the efficiencies are 87.10% for the CirPT-CirPR model and 89.50% for the CirPT-DDPR model, all exceeding the acceptable threshold of 80%.

Co-Catalyzed Suzuki-Miyaura Coupling of Organoboronic Acids and Alkynyl Chlorides Using Potassium Bicarbonate as Base.

Organoboronic acids, some of the most common and widely used organoboron compounds, have not yet been used in the cobalt-catalyzed cross coupling reactions, despite cobalt demonstrating good reactivity with zinc reagents, Grignard reagents, and metal organoborates that are formed by n-butyl lithium or alkaline metal alkoxide salts and organoboron esters. Herein, a highly efficient and practical cobalt-catalyzed coupling reaction of aryl/alkenyl boronic acids and alkynyl chloride under mild reaction conditions is reported. The advantages of the organoboronic acids, along with a broad functional group compatibility and the reaction's tolerance to moisture and air, enable this reaction to be a synthetically useful protocol for the construction of a C(sp2)-C(sp) bond. Lastly, the synthesis of two natural products and a key intermediate of roxadustat was effectively accomplished using the methodology to construct the critical alkynyl-aryl bond.

Femtosecond laser-inscribed in-fiber Mach-Zehnder interferometer for ultra-sensitive small-angle torsion measurement

We propose and demonstrate a novel in-fiber Mach-Zehnder interferometer (MZI), using a femtosecond (FS) laser to inscribe two parallel straight waveguides along both sides of the core-cladding boundary of an optical fiber. Both simulations and experiments demonstrated that constructing a second straight waveguide (WG2) on the opposite side of the fiber core significantly enhances the mode coupling efficiency in fiber, resulting in ultra-sensitive small twist-angle torsion measurement by intensity interrogation. By finely adjusting the waveguide spacing between the WG2 and the fiber core during the FS fabrication process, a large tuning range of ∼ 200 nm for the designable interference wavelength with maximal fringe contrast has been achieved. Through comparative experiments, the proposed in-fiber MZI performs ultra-sensitivity with 17417.92 dB/(rad/mm) over small twist angles from −10° to 0° for the sample “WG1-4/WG2-4” and 19480.57 dB/(rad/mm) over small twist angles from 0° to 10° for the sample “WG1-4/WG2-6”. Besides, the device is insensitive to temperature and strain. The exhibited advantages of high sensitivity, high reproducibility, and low crosstalks promote the proposed in-fiber MZI to be applied in future industrial engineering monitoring and intelligent health monitoring.

Echocardiographic Assessment in Patients with Vascular Ehlers-Danlos Syndrome: Insights from an Unexplored Field.

Vascular Ehlers-Danlos syndrome (vEDS) is an inherited connective tissue disorder characterized by arterial fragility. Celiprolol is a β1-adrenoceptor antagonist with partial β2 agonist activity that has been shown to reduce rates of vascular events in this setting, though the underlying mechanisms are not yet fully understood. Moreover, very few echocardiographic data are available in patients with vEDS. To perform a comprehensive echocardiographic assessment of a cohort of patients with vEDS with or without celiprolol therapy compared with healthy subjects. Twenty patients with genetically confirmed diagnosis of vEDS followed at our Institution (University Hospital of Brescia, Italy) were divided into two groups according to whether or not they were on celiprolol therapy at the maximum recommended dose (400mg daily) for at least 12 months. Both groups were compared to 10 healthy individuals matched for sex, age, body mass index (BMI), and office blood pressure (BP) values. Each participant underwent transthoracic echocardiography with tissue Doppler analysis (TDI) for a comprehensive evaluation of cardiac structure and function. Mean age was 35 years and mean BMI was 21.6 kg/m2. Female sex was prevalent (60%). Left ventricular (LV) internal diameter values tended to be lower in patients with untreated vEDS than in healthy controls (4.33 vs 4.74cm, respectively), though this difference was not statistically significant. Similar data were observed for LV mass index (56.9 vs 68.6 g/m2), stroke volume (56.6 vs 71.6 mL), and E/A ratio (1.26 vs 1.66), whereas an opposite trend was observed for e' lateral (13.2 vs 12.2cm/s). No statistically significant difference was found between groups in terms of other parameters of LV mass, systolic and diastolic function. A normal LV geometry was found in all the cases. Indices of mechano-energetic efficiency and ventricular-arterial coupling were also similar between groups. No patient presented with aortic root dilation, mitral valve prolapse, valve insufficiency of more than mild degree, or valve stenosis of any degree. Our study suggests that patients with vEDS have normal cardiac mass and geometry, as well as normal systolic and diastolic function. Celiprolol therapy does not seem to significantly influence such aspects. Compared with vascular imaging, less stringent follow-up with echocardiography seems reasonable in this setting. Future studies with prospective design should confirm these aspects.

Spectroscopy using a visible photonic lantern at the Subaru Telescope: Laboratory characterization and the first on-sky demonstration on Ikiiki (α Leo) and ‘Aua (α Ori)

Context. Photonic lanterns (PLs) are waveguide devices enabling high-throughput single-mode spectroscopy and high angular resolution. Aims. We aim to present the first on-sky demonstration of a PL operating in visible light, to measure its throughput and assess its potential for high-resolution spectroscopy of compact objects. Methods. We used the SCExAO instrument (a double-stage extreme adaptive optics system installed at the Subaru Telescope) and FIRST mid-resolution spectrograph (R 3000) to test the visible capabilities of the PL on internal source and on-sky observations. Results. The best averaged coupling efficiency over the PL field of view was measured at 51% ± 10%, with a peak at 80%. We also investigated the relationship between coupling efficiency and the Strehl ratio for a PL, comparing them with those of a single-mode fiber (SMF). Findings show that in the adaptive optics regime a PL offers a better coupling efficiency performance than an SMF, especially in the presence of low-spatial-frequency aberrations. We observed Ikiiki (α Leo – mR = 1.37) and ‘Aua (α Ori – mR = −1.17) at a frame rate of 200 Hz. Under median seeing conditions (about 1 arcsec measured in the H band) and large tip or tilt residuals (over 20 mas), we estimated an average light coupling efficiency of 14.5% ± 7.4%, with a maximum of 42.8% at 680 nm. We were able to reconstruct both star’s spectra, containing various absorption lines. Conclusions. The successful demonstration of this device opens new possibilities in terms of high-throughput single-mode fiber-fed spectroscopy in the visible. The demonstrated on-sky coupling efficiency performance would not have been achievable with a single SMF injection setup under similar conditions, partly because the residual tip or tilt alone exceeded the field of view of a visible SMF (18 mas at 700 nm). This emphasizes the enhanced resilience of PL technology to such atmospheric disturbances. The additional capabilities in high angular resolution are also promising but still have to be demonstrated in a forthcoming investigation.

Inverse design of ultra-compact high-efficiency broadband interlayer couplers based on random gratings

Ultra-compact high-efficiency broadband interlayer couplers based on random gratings are inversely designed by particle swarm optimization algorithm. The optimal structure is obtained by adjusting the pixel state to achieve a maximum coupling efficiency in 1550 nm band. The two-layer coupler consists of two vertically overlapping inverse taper waveguides with random gratings. With a short coupling length of 4 μm and interlayer gap of 200 nm, the coupling efficiency reaches 93% at a wavelength of 1550 nm, and exceeds 90% over a broadband wavelength range of 1503∼1600 nm, for both TE and TM mode. The coupling efficiency can maintain no less than 90% at a large waveguide misalignment of >100 nm, exhibiting high process error tolerance. The performance of the 4 μm-long inverse-designed coupler is higher than the conventional waveguide with a much large length of 10 μm. To achieve longer transmission distance, a tri-layer interlayer coupler is proposed by cascading two bi-layer couplers, which exhibits a remarkable coupling efficiency of 85% at a gap of 600 nm, more than 30 times higher than the bi-layer structure. This work may pave the way for the development of ultra-compact high-performance interlayer couplers supporting high-integration Si-based photonic integrated circuits.

Highly Efficient Single Photon Coupling via Surface Plasmons into Single-Mode Optical Fiber

Quanta of light (single photon) play as one of the building blocks of photonic based quantum computations, sensing, and communications. This makes a necessity to develop practical approaches for tuning, guiding, and coupling of single photons in photonic circuits for viable applications. Interaction and coupling efficiency of single photon into optical fibers is a technical bottleneck of quantum optics and should be addressed by novel design and materials. Here, we introduce a fiber-based micro-photonic design to directly coupling of the emitted single-photon to the core of a single mode fiber (SMF). The results of the simulation indicate that the emission of single photon source on a D-shaped SMF coated by a thin plasmonic film, provide remarkable amplifying of the evanescent field by confined surface plasmons into the SMF. The numerical analysis of different types and thicknesses of plasmonic materials by finite element method (FEM) is conducted to study the propagation vectors along the SMF as a function of the emission angle and wavelength of the single photon source. The results revealed that by the optimum thickness of the tantalum layer as novel plasmonic material, the best record of coupling efficiency can be achieved in the fiber optics communication region (λ ∼ 1550 nm). This approach sheds light on novel plasmonic-assisted coupling and promises a functional strategy for single photon manipulation in various fields of quantum optics.

Atrial pacing improves mitochondrial function in peripheral blood mononuclear cells in patients with cardiac implantable electronic devices.

Mitochondrial dysfunction contributes significantly to the development of atrial fibrillation (AF). Conflicting data regarding the atrial pacing and the risk of AF existed, and the impact of atrial pacing on mitochondrial function remains unknown. Therefore, we sought to examine the association between atrial pacing percentage and mitochondrial function in patients with cardiovascular implantable electronic devices (CIEDs) with atrial pacing capability. This is a cross-sectional study involving 183 patients with CIEDs with atrial pacing capability. The oxidative stress and mitochondrial function were determined in peripheral blood mononuclear cells (PBMCs). Among 183 patients, 55.7% had permanent pacemakers, 7.7% had defibrillators, and 36.6% had cardiac resynchronization therapy. Mean age was 67.5 ± 14.7 yr with 51% being male. Mean left ventricular ejection fraction (LVEF) was 53.9 ± 16.8%. We demonstrated that the presence of atrial pacing above 50% correlated with higher levels of mitochondrial spared respiratory capacity (P = 0.043) and coupling efficiency (P = 0.045). After adjusting with multiple linear regression for age, sex, LVEF, history of AF, sick sinus syndrome, comorbidities, estimated glomerular filtration rate (eGFR), cardiac resynchronization therapy (CRT), and percentage of ventricular pacing, our findings revealed a statistically significant association between a higher percentage of atrial pacing and increased spared respiratory capacity (β, 0.217, P = 0.046), lower nonmitochondrial respiration (β, -0.230; P = 0.023), and proton leak (β, -0.247; P = 0.022). We demonstrated that atrial pacing enhances mitochondrial performance in PBMCs and left ventricular contractile performance in patients with CIEDs. This observation may serve as an additional support for the preventive effect of atrial pacing in the prevention of atrial arrhythmia.NEW & NOTEWORTHY Atrial pacing enhances mitochondrial spare respiratory capacity and reduces proton leak. This finding may provide further evidence supporting the preventive role of atrial pacing in reducing the risk of atrial fibrillation in patients with cardiac implantable electronic devices.

Efficient coupling between photonic waveguides and III-nitride quantum emitters in the UV-visible spectral range

Efficient coupling between photonic waveguides and III-nitride quantum emitters in the UV-visible spectral range

Coupling and coordination of food security and agricultural carbon emission efficiency: Changing trends, influencing factors, and different government priority scenarios

Seeking a balance between food security and carbon mitigation is key to achieving sustainable agricultural development. This study evaluates the coupling coordination degree (CCD) between the food security index (FSI) and agricultural carbon emission efficiency (ACEE) in China from 2010 to 2021 using the coupled coordination model. By adjusting the model coefficients, different government priority scenarios are simulated to explore their impact on CCD. The Geodetector method is employed to identify the influencing factors of CCD, investigate their interactions, and assess the differences in these factors across various government priority settings. The average CCD between FSI and ACEE exhibits a notable upward trend, rising from 0.4583 in 2010 to 0.6595 in 2021. Furthermore, regional disparities are widening, particularly in the major production areas. Catch-up effects exist within regions. Policy simulations showed staged interactions between food security and agricultural carbon efficiency, shifting from food security to balanced production and ecology, then to prioritizing low-carbon production for food security. Adjusting policy priorities can effectively improve coupling coordination in the short term, with increasing impact as priority shifts. CCD is influenced by policy, technology, economy, and society, varying with policy priorities. In the baseline scenario, key factors for CCD include the urban-rural income gap, technological advancement, urbanization, and farmers' education level. When the government prioritizes food security, the impact of narrowing income gaps and agricultural industry agglomeration becomes more pronounced. Conversely, emphasizing carbon emission efficiency enhances the influence of technological advancements and urbanization on CCD. Tailoring agricultural production strategies to local conditions and emphasizing interactive effects among factors is crucial for achieving environmentally friendly and high-quality agricultural development goals.

Streamlined line-defect taper design for broadband and efficient mode coupling: connecting a silicon strip with a planar valley photonic crystal zigzag interface.

The integration of planar valley photonic crystal (VPC) interfaces into high-speed data communication chips markedly improves data rates and system robustness. This Letter presents a novel, to the best of our knowledge, edge coupler, termed the line-defect taper, which is crucial for efficient and broadband light delivery to planar VPC interfaces via silicon strip waveguides. The coupling performance of the line-defect taper is evaluated through full-wave three-dimensional finite-element simulations. The results demonstrate a -3 dB transmission bandwidth of 65.5 nm, covering 41.2% of the topological bandgap, and a -1 dB transmission bandwidth of 16.3 nm, accounting for 10.3%. With its compact design (only 3.6 µm in length), simplicity, and scalability, the line-defect taper is a promising candidate for integration into densely packed chips, highlighting its potential in advancing on-chip devices.

High coupling efficiency with large axial direction coupling adjustment range in water-jet guided laser

In the traditional water-jet guided laser (WJGL) processing system, convex lens is used to focus Gaussian laser beam, where the waist and divergence angle are constrained. The focal depth is small, and there are problems such as divergence angle and aberration, which results in the difficult coupling adjustment because the adjustment range of laser coupling to water-jet fiber is limited to the Rayleigh range. In this study, non-diffraction laser (NDL) is generated by an axicon, which has the characteristics of small central spot and large non-diffraction range (NDR). The axial random coupling is realized in the NDR, and the problem of axial coupling between the focused laser and the water-jet generated by nozzle micro-hole is solved. Besides, this paper presents a novel technique to generate NDL by the combination of concave axicon (CCA) and convex axicon (CVA), which solves the small cone angle of the single CVA and the non-modulation defect of the corresponding optical and mechanical structure, and extends the starting point of the NDR to improve the coupling utilization rate of the NDR and the flexibility of the system. The focusing and coupling transmission characteristics of convex lens and axicons mode in WJGL are compared and analyzed. The generated NDL in the NDR at the axial reference coordinate point position of 50 mm and 70 mm is successfully coupled into the water-jet fiber. After the coupling transmission of 20 mm, the coupling efficiency, the morphology of the transmitted spot and the peak power density were basically the same, and the coupling efficiency of the central spot was about 81 %. However, the output spot peak power density and coupling efficiency decrease sharply when the axial coupling deviation exceeds 5 mm adopting convex lens. In contrast, the NDL can achieve a random coupling with high axial coupling tolerance in NDR. The research provides a solution for efficient adjustment and transmission of laser coupling into water-jet in highly stable WJGL.

A coupled peridynamics–smoothed particle hydrodynamics model for fluid–structure interaction with large deformation

Fluid–structure interaction (FSI) is ubiquitous in various engineering disciplines, and effectively managing FSI often appears to be the key for successful failure analysis and safety-oriented design. Smoothed particle hydrodynamics (SPH) serves as a potent nonlocal meshfree method for fluid dynamics modeling, while peridynamics (PD) demonstrates exceptional capability in addressing structural dynamics involving large deformations and discontinuities. Thus, leveraging their respective strengths in a combined approach holds significant promise for tackling FSI challenges. In this work, we propose a new peridynamics–smoothed particle hydrodynamics (PD-SPH) coupling model for addressing FSI. A stable and efficient coupling algorithm for data transfer between PD and SPH is put forward. In this coupling strategy, a PD particle directly participates in solving the SPH governing equations when it is identified to be within the support domain of an SPH particle. This can be done since the SPH quantities including the density, velocity, and pressure of a PD particle are naturally attainable within the framework of non-ordinary state-based peridynamics theory. Concurrently, in solving PD governing equations, reaction forces from SPH particles act as external forces for PD particles, determined straightforwardly through Newton's third law. As such, the proposed PD-SPH coupling strategy is straightforward to implement and offers high computational efficiency. Validation examples demonstrate that the proposed PD-SPH coupling model is computationally robust and adept at capturing physical phenomena in diverse FSI scenarios involving breaking free surfaces of fluid and large structural deformations of solid. Moreover, the proposed PD-SPH coupling model is flexible introducing no constraint conditions for applications and can accommodate different particle resolutions for PD and SPH domains. These features enable a broad application range of the proposed PD-SPH coupling model including simulations of explosion-induced soil fragmentation, rock fracture, and concrete dam failure, which will be conducted by authors in the near future.

Homogeneous crystallization of MA-free, wide-bandgap perovskite films via self-assembled monolayer capping for laminated silicon/perovskite tandem solar cells

Methylammonium (MA)-free wide-bandgap perovskite films with improved thermal/light stabilities have gained considerable attention for its application in silicon/perovskite tandem solar cells. However, compared to their MA counterparts, MA-free films often suffer from fast crystallization, resulting in uneven surface morphology, poor crystalline features, and excess PbI2 impurities. To modulate the crystallization dynamics of MA-free wide-bandgap Cs0.22FA0.78Pb(Br0.15I0.85)3 films, this study proposes a self-assembled monolayer (SAM)-capped crystallization strategy, wherein C42H52N6O4RuS2 (Z907) is added to the isopropanol antisolvent in the one-step solution process. The optimized Cs0.22FA0.78Pb(Br0.15I0.85)3 film has a wide bandgap of 1.68 eV with superior morphological/crystalline properties, enhanced thermal/moisture stability, and improved interfacial energy‐level alignment. These favorable characteristics are attributed to the efficient coupling between the positive ion vacancies in the precursor, the −SCN and –COOH functional groups in Z907, and the superhydrophobic nonyl chains in the Z907 SAM. The semitransparent perovskite solar cells (PSCs) built with the optimized Cs0.22FA0.78Pb(Br0.15I0.85)3 films demonstrate substantially high power conversion efficiencies (PCEs) of 21.63 %@0.09 cm2 and 19.12 %@1 cm2. Furthermore, based on the high-efficiency PSCs, the corresponding two-terminal laminated silicon/perovskite tandem solar cells achieved record-high PCEs of 32.07 %@0.09 cm2 and 28.32 %@1 cm2 with negligible hysteresis and improved humidity/thermal stability.

Copper-Catalyzed Aerobic Cross-Dehydrogenation Coupling of Indoles for Synthesis of 2,3'-Bisindoles.

2,3'-Bisindoles with C-C linkages have attracted interest in medicinal chemistry, yet their synthesis is intricate with many steps. Notably, direct C-H/C-H cross-coupling of non-directed heteroaromatics remains challenging, often requiring precious metals and oxidants to enhance coupling efficiency. Herein, we present a copper-catalyzed C-H/C-H cross-coupling method for N-substituted indoles without directing groups, facilitated by molecular oxygen under gentle conditions. It showed reasonable functional group compatibility and provided one-pot access to a variety of 2,3'-bisindoles derivatives in moderate to good yields.

Mechanism of airborne sound absorption through triboelectric effect for noise mitigation

Mitigating broadband noise with passive airborne sound absorbers has been a long-lasting challenge, particularly for low-frequency anthropogenic sounds below kilohertz with long wavelengths, which require bulky materials for effective absorption. Here, we propose a strategy that utilizes local triboelectric effect and in-situ electrical energy dissipation mechanism for airborne sound absorption. This approach involves a fundamentally different mechanism that converts airborne sound into electricity for energy dissipation, in contrast to conventional mechano-thermal energy conversion mechanisms. We establish an equivalent acoustic impedance model to provide theoretical analysis of the underlying sound absorption mechanisms, with a theoretical maximum mechano-electro-thermal coupling efficiency approaching 100% under optimal conditions. We design fibrous triboelectric composite foam materials accordingly and show their substantially boosted acoustic absorption performance experimentally, where the adoption of diverse triboelectric material pairs validates that a larger difference in material charge affinities intensifies the local triboelectric effect and results in higher acoustic absorbing performance.