Coupling Configuration Research Articles

A Compact Quadruplexer-Integrated Filtering Power Divider

A compact quadruplexer with the functions of frequency division, frequency selection, and power splitting/combining is presented in this article. Four tri-mode stub-loaded resonators were adopted to construct the compact multifunctional quadruplexer with a third-order filtering response. The four-channel passbands of the quadruplexer were controlled and realized independently by using the distribution coupling configuration. The output coupling structure was designed to be symmetrical with equal power division for each channel. To achieve a satisfactory isolation performance, a resistor was loaded between the open ends of the output coupled lines for each channel. A microstrip multifunctional quadruplexer operating at 1.1, 1.44, 1.73, and 2.06 GHz was fabricated. The prototype circuit size of the multifunctional quadruplexer was only approximately 0.4 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> × 0.59 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> . Moreover, the output isolations were >27 dB within the entire frequency bands.

Chimera states through invariant manifold theory

We establish the existence of chimera states, simultaneously supporting synchronous and asynchronous dynamics, in a network of two symmetrically linked star subnetworks of identical oscillators with shear and Kuramoto–Sakaguchi coupling. We show that the chimera states may be metastable or asymptotically stable. If the intra-star coupling strength is of order ɛ, the chimera states persist on time scales at least of order 1/ɛ in general, and on time-scales at least of order 1/ɛ 2 if the intra-star coupling is of Kuramoto–Sakaguchi type. If the intra-star coupling configuration is sparse, the chimeras are asymptotically stable. The analysis relies on a combination of dimensional reduction using a Möbius symmetry group and techniques from averaging theory and normal hyperbolicity.

Optical Power Scale Realization by Laser Calorimeter after 45 Years of Operation.

To calibrate laser power and energy meters, the National Institute of Standards and Technology (NIST) uses several detector-based realizations of the scale for optical radiant flux; these realizations are appropriate for specific laser power/energy ranges and optical coupling configurations. Calibrations from 1 µW to 2 W are currently based upon calorimeters. Validation by comparisons against other primary representations of the optical watt over the last two decades suggests the instruments operate well within their typical reported uncertainty level of 0.86 % with 95 % confidence. The dominant uncertainty contribution in the instrument is attributable to light scattered by the legacy window, which was not previously recognized. The inherent electro-optical inequivalence in the calorimeter's response was reassessed by thermal modeling to be 0.03 %. The principal contributions to the overall inequivalence were corrected, yielding a shift in scale representation under 0.2 % for typical calibrations. With updates in several uncertainty contributions resulting from this reassessment, the resulting combined expanded uncertainty (k = 2) is 0.84 %, which is essentially unchanged from the previous result provided to calibration customers.

Transportable mid-infrared laser heterodyne radiometer operating in the shot-noise dominated regime.

A transportable laser heterodyne radiometer (LHR) based on an external cavity quantum cascade laser, operating in the mid-infrared (mid-IR) around 8 µm, was developed for ground-based remote sensing of multiple greenhouse gases. A newly available novel flexible mid-IR polycrystalline fiber was first exploited to couple solar radiation, real-time captured using a portable sun-tracker, to the LHR receiver. Compared to free space coupling of sunlight, the technique usually used nowadays in the mid-IR, such fiber coupling configuration makes the LHR system readily more stable, simpler, and robust. Operation of the LHR with quasi-shot-noise limited performance was analyzed and experimentally achieved by optimizing local oscillator power. To the best of our knowledge, no such performance approaching the fundamental limit has been reported for a transportable LHR operating at a long mid-IR wavelength around 8 µm. CH4 and N2O were simultaneously measured in the atmospheric column using the developed mid-IR LHR. The experimental LHR spectrum of CH4 and N2O was compared and is in good agreement with a referenced Fourier-transform infrared spectrum from the Total Carbon Column Observing Network observation site and with a simulation spectrum from atmospheric transmission modeling.

Effects of classical random external field on the dynamics of entanglement in a four-qubit system

We investigate the dynamics of entanglement through negativity and witness operators in a system of four non-interacting qubits driven by a classical phase noisy laser characterized by a classical random external field (CREF). The qubits are initially prepared in the GHZ-type and W-type states and interact with the CREF in two different qubit-field configurations, namely, common environment and independent environments in which the cases of equal and different field phase probabilities are distinguished. We find that entanglement exhibits different decaying behavior, depending on the input states of the qubits, the qubit-field coupling configuration, and field phase probabilities. On the one hand, we demonstrate that the coupling of the qubits in a common environment is an alternative and more efficient strategy to completely shield the system from the detrimental impacts of the decoherence process induced by a CREF, independent of the input state and the field phase probabilities considered. Also, we show that GHZ-type states have strong dynamics under CREF as compared to W-type states. On the other hand, we demonstrate that in the model investigated the system robustness’s can be greatly improved by increasing the number of qubits constituting the system.

Revealing the CO Coverage-Driven C-C Coupling Mechanism for Electrochemical CO2 Reduction on Cu2O Nanocubes via Operando Raman Spectroscopy.

Electrochemical reduction of carbon dioxide (CO2RR) is an attractive route to close the carbon cycle and potentially turn CO2 into valuable chemicals and fuels. However, the highly selective generation of multicarbon products remains a challenge, suffering from poor mechanistic understanding. Herein, we used operando Raman spectroscopy to track the potential-dependent reduction of Cu2O nanocubes and the surface coverage of reaction intermediates. In particular, we discovered that the potential-dependent intensity ratio of the Cu–CO stretching band to the CO rotation band follows a volcano trend similar to the CO2RR Faradaic efficiency for multicarbon products. By combining operando spectroscopic insights with Density Functional Theory, we proved that this ratio is determined by the CO coverage and that a direct correlation exists between the potential-dependent CO coverage, the preferred C–C coupling configuration, and the selectivity to C2+ products. Thus, operando Raman spectroscopy can serve as an effective method to quantify the coverage of surface intermediates during an electrocatalytic reaction.

Ultra-strong mode confinement at semishell metal/insulator/semiconductor interface for nanolaser

Metal/insulator/semiconductor structure, as a typical interface in conventional electrical and optoelectronic devices, can also act as a plasmon-exciton coupling configuration for designing new concept nanophotonic devices, such as plasmon nanolaser, which is promising to play a coherent light source for nanophotonic integration owing to the spatial localization of surface plasmon (SP). Therefore, it is very important to construct a proper configuration and optimize the nanophotonic performance. In this paper, we designed the Al-semishell structure on ZnO nanorod with SiO2 insulator layer, and further realized plasmonic lasing with high performance. The simulation demonstrated a small effective mode area and high effective index of the semishell ZnO nanocavity with a thickness-optimized dielectric layer, while the experiment revealed plasmon lasing with low threshold (27 MW/cm2) and high quality factor (Q = 485), due to the ultra-strong optical confinement. What's more, the plasmon-exciton coupling mechanism of the plasmonic lasing was further investigated through systematically analyzing about lasing mode shift, as well as temperature-dependent and time-resolved photoluminescence (PL). Quite different from electron-hole plasma (EHP) effect in photonic nanolaser from bare ZnO, the weak dependence of temperature on the PL decay life in semishell ZnO plasmonic nanolaser also reveals the coupling of SP-exciton which accelerates the temporal response under direct laser modulation. The presented results create the possibility of highly integrated coherent light sources operating at extremely high speeds.

Power scaling of continuous-wave second harmonic generation in a MgO:PPLN ridge waveguide and the application to a compact wavelength conversion module.

The power scaling of continuous-wave (CW) second harmonic generation (SHG) in a MgO:periodically poled lithium niobite (PPLN) ridge waveguide is investigated. The nonlinear coefficient and propagation loss factors of the MgO:PPLN waveguide are verified for future reference. The MgO:PPLN waveguide structure is determined according to a practical fiber coupling configuration, as well as the theoretical model of output power characteristics. Utilizing the designed MgO:PPLN waveguide, the 775 nm SHG power successfully reaches up to 4.02 W at an incident power of 7 W with overall conversion efficiency of 58%. Finally, a compact all-fiber waveguide conversion module is demonstrated for verifying the feasibility of commercial applications.

In-Fiber Butt-Coupled Spherical Microcavity With Whispering Gallery Mode and Fabry-Perot Resonances

An integrated in-fiber coupling configuration for simultaneously exciting whispering gallery mode (WGM) and Fabry-Perot (FP) resonances in one cavity is proposed and demonstrated experimentally. The WGMs traveling circularly in both clockwise and counter-clockwise directions are simultaneously excited by perpendicularly injecting the light from the single-mode-fiber (SMF) core into a polymeric microsphere embedded in the femtosecond laser micromachined coupling structure. While the standing wave between the two axial interfaces of the microsphere and its external media results in a spherical FP resonator, meaning that the WGM and the FP resonances coexist in the same spherical cavity. The superposition of WGM and FP resonances results in asymmetric Fano-like lineshape, which is of high importance for optical fiber sensors, filters, and switches due to its sharp slope around the resonant wavelength. Experimental results show that asymmetric spectral lineshape can be achieved even as the spatial coupling gap is larger than the wavelength, indicating that the proposed coupler has higher fabrication tolerance than the evanescent field-based coupling configuration. Such an integrated coupling configuration provides an effective method for the coupling between the optical fiber and WGM cavities made of any functional material by liberating them from the phase-matching condition and enriching the functionality by importing other resonance into the same cavity.

Discontinuous coupling and transition from synchronization to an intermittent transient chimera state

The coexistence of coherent and incoherent clusters, which is named chimera state, has been observed in various coupling configurations. The majority of the studies have considered a static scheme for the network. In this paper, the synchronization patterns of a time-varying network with discontinuous coupling (on/off links) are studied. At first, the prerequisites for the synchronization of continuous and discontinuous coupling are found by the master stability function method. It is observed that when the network with continuous coupling is set in the synchronous region, changing the coupling to a discontinuous one leads to the emergence of a pattern consisting of alternating synchronization, asynchronization, and chimera state. We call this pattern intermittent transient chimera. The study is completed by investigating the effect of the rate of discontinuity on the network behavior.

The Effect of Atmosphere-Ocean Coupling on the Structure and Intensity of Tropical Cyclone Bejisa in the Southwest Indian Ocean

A set of numerical simulations is relied upon to evaluate the impact of air-sea interactions on the behaviour of tropical cyclone (TC) Bejisa (2014), using various configurations of the coupled ocean-atmosphere numerical system Meso-NH-NEMO. Uncoupled (SST constant) as well as 1D (use of a 1D ocean mixed layer) and 3D (full 3D ocean) coupled experiments are conducted to evaluate the impact of the oceanic response and dynamic processes, with emphasis on the simulated structure and intensity of TC Bejisa. Although the three experiments are shown to properly capture the track of the tropical cyclone, the intensity and the spatial distribution of the sea surface cooling show strong differences from one coupled experiment to another. In the 1D experiment, sea surface cooling (∼1 °C) is reduced by a factor 2 with respect to observations and appears restricted to the depth of the ocean mixed layer. Cooling is maximized along the right-hand side of the TC track, in apparent disagreement with satellite-derived sea surface temperature observations. In the 3D experiment, surface cooling of up to 2.5 °C is simulated along the left hand side of the TC track, which shows more consistency with observations both in terms of intensity and spatial structure. In-depth cooling is also shown to extend to a much deeper depth, with a secondary maximum of nearly 1.5 °C simulated near 250 m. With respect to the uncoupled experiment, heat fluxes are reduced from about 20% in both 1D and 3D coupling configurations. The tropical cyclone intensity in terms of occurrence of 10-m TC wind is globally reduced in both cases by about 10%. 3D-coupling tends to asymmetrize winds aloft with little impact on intensity but rather a modification of the secondary circulation, resulting in a slight change in structure.

Synchronization of polarization chaos in mutually coupled free-running VCSELs.

We numerically demonstrate and analyze polarization chaos synchronization between two free-running vertical cavity surface emitting semiconductor lasers (VCSELs) in the mutual coupling configuration under two scenarios: parallel injection and orthogonal injection. Specifically, we investigate the effect of external parameters (the bias current, frequency detuning and coupling coefficient) and internal parameters (the linewidth enhancement factor, spin-flip relaxation rate, field decay rate, carrier decay rate, birefringence and dichroism) on the synchronization quality. Finally simulation results confirm that in the parallel injection, chaotic synchronization can reach a cross-correlation coefficient of 0.99 within a range of parameter mismatch ±12%. On the other hand, the chaos synchronization for orthogonal injection only reaches a cross-correlation coefficient of 0.95 within a range of parameter mismatch ±3%.

Evaluation of highly entangled states in asymmetrically coupled three NV centers by quantum simulator

Despite numerous efforts, the coupling between randomly arranged multi-NV centers and also resonators has not been improved significantly mainly due to our limited knowledge of their free evolution time for entanglement (2τent). Here, we demonstrate very strong coupling between three NV centers by using a simulated triple electron-electron resonance experiment based on a quantum (UC) gate on an IBM quantum simulator with 2τent ∼ 12.5 μs arranged in a triangular configuration. Interestingly, through breaking, the symmetry of couplings an even lower 2τent ∼ 6.3 μs can be achieved. This simulation not only explains the luminescence spectra in recently observed three NV centers but also shows a large improvement of the entanglement in artificially created structures through a cyclic redistribution of couplings. Realistically disordered coupling configurations of NV center qubits with short time periods and high (0.89–0.99) fidelity of states clearly demonstrate the possibility of accurate quantum registers operated at room temperature.

Evaluation of natural frequency, Campbell diagram and forced torsional vibration of deepwell pumps for the marine, oil and gas industry

Deepwell marine and offshore pumps need to design in a way to present high performance and reliable lifetime. Deepwell pumps should be designed in a way to operate under offshore conditions. In order to investigate the resonance and find critical rotational speeds of the pump, it is needed to find the rotational natural frequency for undamped model. In order to avoid any resonance, the intersection points between natural frequency and excitation (1X and 2X) should not be in the interval of 90%-110% of operating speed, based on API standard (API 610). Deepwell pump structure is combination of motor, motor-shaft coupling and pumping configuration. Based on the size of tank and type of ship the length of whole deepwell pump can be more than 40 meters. Elastic rotating shafts connect with appropriate shaft-couplings with needed numbers of impellers and inducer. Small and linear angle of rotation theory are used to extract natural frequencies of deepwell pumps. Different damping scenarios are illustrated in detail. Holzer method is implemented to analyse torsional forced vibration. Free-free boundary conditions considered. Combination of discrete model, lumped mass model and finite element method are employed to present the Campbell diagram. Parametric strategy is used for forced torsional vibration analysis. It is found that how to model and consider the effective length of intermediate shaft in pumping configuration has effect on second natural frequency. It is seen that the first natural frequency of the whole system is highly depended on modelling of motor-shaft coupling. The results are compared when the whole pump is model by lamped mass model and finite element model. Results of this paper suggest that combination of three mentioned methods is acceptable and accurate. It is shown that Holzer method is suitable for torsional forced vibration analysis. The developed codes are verified with findings in the literature.

Coordinated Control of Battery Energy Storage System Based on Fuzzy Logic for Microgrid with Modified AC Coupling Configuration

Coordinated Control of Battery Energy Storage System Based on Fuzzy Logic for Microgrid with Modified AC Coupling Configuration

High-speed and high-power germanium photodetector with a lateral silicon nitride waveguide

Up to now, the light coupling schemes of germanium-on-silicon photodetectors (Ge-on-Si PDs) could be divided into three main categories: (1) vertical (or normal-incidence) illumination, which can be from the top or back of the wafer/chip, and waveguide-integrated coupling including (2) butt coupling and (3) evanescent coupling. In evanescent coupling the input waveguide can be positioned on top, at the bottom, or lateral to the absorber. Here, to the best of our knowledge, we propose the first concept of Ge-on-Si PD with double lateral silicon nitride ( Si 3 N 4 ) waveguides, which can serve as a novel waveguide-integrated coupling configuration: double lateral coupling. The Ge-on-Si PD with double lateral Si 3 N 4 waveguides features uniform optical field distribution in the Ge region, which is very beneficial to improving the operation speed for high input power. The proposed Ge-on-Si PD is comprehensively characterized by static and dynamic measurements. The typical internal responsivity is evaluated to be 0.52 A/W at an input power of 25 mW. The equivalent circuit model and theoretical 3 dB opto-electrical (OE) bandwidth investigation of Ge-on-Si PD with lateral coupling are implemented. Based on the small-signal (S21) radio-frequency measurements, under 4 mA photocurrent, a 60 GHz bandwidth operating at − 3 V bias voltage is demonstrated. When the photocurrent is up to 12 mA, the 3 dB OE bandwidth still has 36 GHz. With 1 mA photocurrent, the 70, 80, 90, and 100 Gbit/s non-return-to-zero (NRZ) and 100, 120, 140, and 150 Gbit/s four-level pulse amplitude modulation clear openings of eye diagrams are experimentally obtained without utilizing any offline digital signal processing at the receiver side. In order to verify the high-power handling performance in high-speed data transmission, we investigate the eye diagram variations with the increase of photocurrents. The clear open electrical eye diagrams of 60 Gbit/s NRZ under 20 mA photocurrent are also obtained. Overall, the proposed lateral Si 3 N 4 waveguide structure is flexibly extendable to a light coupling configuration of PDs, which makes it very attractive for developing high-performance silicon photonic integrated circuits in the future.

Co-simulating a greenhouse in a building to quantify co-benefits of different coupled configurations

ABSTRACT Recent findings suggest that rooftop greenhouses could be more efficient when combined with waste streams in buildings, but there is a gap in quantification of the combined performance of building integrated greenhouses. This paper addresses this deficit for school buildings in London, UK, where urban agriculture is of increasing interest. A building energy simulation (BES) of an archetype school building is developed in EnergyPlus and co-simulated with a validated greenhouse energy simulator (GES). The performance of different greenhouse-building coupling configurations is evaluated to estimate the potential for crop growth, heat recovery and reduction in ventilation demand, through a sensitivity analysis and parametric study. Our results show that a 250 m greenhouse on the top floor of the school could produce 6t lettuce with half the energy demand of the same standalone greenhouse. Trade-offs across increase in humidity, yields, and energy efficiency indicate the importance of modelling to ensure optimal designs.

Three-phase distribution transformer connections modeling based on matrix operation method by phase-coordinates

This paper proposes a matrix operation method for modeling the three-phase transformer by phase-coordinates. Based on decoupling theory, the 12 × 12 dimension primitive admittance matrix is obtained at first employing the coupling configuration of the windings. Under the condition of asymmetric magnetic circuits, according to the boundary conditions for transformer connections, the transformers in different connections enable to be modeling by the matrix operation method from the primitive admittance matrix. Another purpose of this paper is to explain the differences of the phase-coordinates and the positive sequence parameters in the impedances of the transformers. The numerical testing results in IEEE-4 system show that the proposed method is valid and efficient.

Performance Evaluation of Coupling Variants for an Active Middle Ear Implant Actuator: Output, Conductive Losses, and Stability of Coupling With Ambient Pressure Changes.

This study aims to investigate the performance of an active middle ear implant actuator for various coupling configurations. Actuator output and conductive losses were measured, and the stability of coupling was evaluated by challenging the link between actuator and ossicles through pressure events in magnitudes that occur in daily life. Actuator coupling efficiency and the occurrence of conductive losses were measured in 10 temporal bones through laser Doppler vibrometry on the stapes footplate for various coupling types (incus short process with and without laser hole, incus long process, stapes head). To test the stability of coupling, actuator output was measured before and after daily-life pressure events that were simulated; Valsalva maneuvers (500 cycles of -40 to +60 hPa) and jumping into a swimming pool and diving 3 m deep (a step change of 300 hPa). Actuator output was similarly high for all types of coupling to the incus (short process and long process) and most efficient for coupling to the stapes head. Conductive losses occurred in two temporal bones (TBs) for short process coupling but for seven TBs for coupling to the incus long process. All coupling types were stable and did not lose efficiency after pressure events in the low-frequency range (<1 kHz). Losses in output of 13 to 24 dB were observed in one TB at frequencies from 3 to 6 kHz. Actuator output was similarly high for all types of coupling to the incus but coupling to the incus long process led to a higher occurrence of conductive losses. All three coupling configurations connected the actuator securely to the ossicular chain, under variations of barometric pressure that can be expected in daily life.

Interaction induced non-reciprocal three-level quantum transport* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11874156 and 11904111) and the Project funded by China Postdoctoral Science Foundation (Grant No. 2019M652684).

Besides its fundamental importance, non-reciprocity has also found many potential applications in quantum technology. Recently, many quantum systems have been proposed to realize non-reciprocity, but stable non-reciprocal process is still experimentally difficult in general, due to the needed cyclical interactions in artificial systems or operational difficulties in solid state materials. Here, we propose a new kind of interaction induced non-reciprocal operation, based on the conventional stimulated-Raman-adiabatic-passage (STIRAP) setup, which removes the experimental difficulty of requiring cyclical interaction, and thus it is directly implementable in various quantum systems. Furthermore, we also illustrate our proposal on a chain of three coupled superconducting transmons, which can lead to a non-reciprocal circulator with high fidelity without a ring coupling configuration as in the previous schemes or implementations. Therefore, our protocol provides a promising way to explore fundamental non-reciprocal quantum physics as well as realize non-reciprocal quantum device.