Effects Of Coupling Coefficient Research Articles

Comparison of Series/Series and Parallel/Series Resonance Circuit in 1.5 kW Inductive Wireless Power Transfer for EV Applications

Wireless power transfer system plays a key role in the present and future days, because of their upgraded comfort and safety and their merits of less green-house gas (GHG) emissions, cell phones, laptops and electric vehicle charging. In this paper, the basic two resonance circuits were analyzed using an inductive wireless power transfer (IWPT) system, at 1.5 kW, 120-mm, and 85 kHz resonance frequencies. It includes analyzing, designing, and comparing this resonance circuit to choose a suitable resonant circuit for the particular application of an IWPT system. The main analysis and comparison were: Mutual Inductance Effect (Misalignment), stresses on the components, Effect of mutual inductance on the efficiency, Effect of distance on the efficiency, Effect of frequency on the efficiency, Effect of the coupling coefficient (k) on the efficiency and transferred power, Effect of coupling coefficient (k) on the input impedance, Effect of distance on the coupling coefficient (k) and Mutual inductance, and both S/S and P/S circuits have same battery output dc power, current, voltage levels. Both resonance circuits designing formulas derived, electrical parameters are calculated for the given wireless power charger level reaches SAEJ2954 standards. In the end, both resonance circuits are verified through MATLAB simulation of the equivalent circuits.

Two-dimensional coherent optical en/decoder based on serially coupled dumbbell microring resonator

Free spectral range (FSR) of reflection spectrum of micro-ring resonator restricts the improvement in user capacity of the optical code division multiple access (OCDMA) system using micro-ring resonator array. Vernier effects can expand FSR of cascaded optical microring resonator. Based on vernier effect, a novel two-dimensional coherent optical en/decoder using serially coupled dumbbell micro-ring resonator is proposed in this paper. The theoretical model of optical transmission for series dumbbell-shaped microring resonators is established. The relation between the suppression of pseudo-modes in optical reflection spectrum and the coupling coefficient is analyzed in detail. The effects of coupling coefficient, processing error and chip rate on the performance of series dumbbell microring resonator optical en/decoder are studied. The en/decoding simulation experiments are carried out on a series dumbbell-shaped micro-ring resonator with radius of 40 μm-30 μm-40 μm respectively. The results show that comparing with the traditional series micro-ring resonator with radius of 40 μm-40 μm-40 μm respectively, the FSR value of dumbbell microcavity is increased by 4 times and the user capacity can increase exponentially. Meanwhile, the ratio of autocorrelation peak to maximum wing (<i>P</i>/<i>W</i>) and the cross-correlation ratio (<i>P</i>/<i>C</i>) are increased by about 33% and 8%, respectively.

Superimposed long period gratings based mode converter in few-mode fiber

Mode-division multiplexing (MDM), as one of the promising techniques for overcoming current limitation of transmission capacity in single-mode fibers (SMFs), has attracted considerable attention. A key component in the MDM system is a mode converter, which makes conversion between the fundamental mode and the higher-order mode. Many mode converters have been demonstrated, such as spatial light modulators, phase plates, silicon-based asymmetrical directional couplers, fiber-based photonic lantern, and long period fiber grating (LPFG). Compared with other methods, mode converter used LPFG is a very feasible technique, which has the advantages of small size, low loss, low backward noise, high coupling efficiency and easy fabrication. However, the limitation of the mode converter is relatively narrow bandwidth. In this paper, a novel broadband all-fiber mode converter is proposed, in which two long period fiber gratings (LPFGs) with different periods are fabricated in the same spatial domain of few-mode fiber to achieve coupling from LP<sub>01</sub> to LP<sub>11</sub>, thus forming superimposed long period fiber gratings (SLPFGs). The influences of grating parameters, such as the interval between two periods, the length of grating and the coupling coefficient on the mode converter, are analyzed by numerical simulation. It is found that the gap between the two resonant wavelengths becomes smaller with the periodic interval decreasing, which can form one rejection band when the gap is small enough, thus a broadband mode converter can be realized. The corresponding bandwidth at a conversion efficiency of 10 dB is about twice that of traditional LPFG. Moreover, with the increase of grating length, the conversion efficiency first increases and then decreases, because coupling efficiency experiences deficient coupling, full coupling and over coupling. The effect of coupling coefficient on converter is similar to that of grating length. According to the numerical results, grating I is fabricated with <inline-formula><tex-math id="M3">\begin{document}${\varLambda _1} = 673\;{\text{μ}}{\rm m} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20181674_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20181674_M3.png"/></alternatives></inline-formula>, 35-period. After that, the platform is rotated 180° and grating II is fabricated with <inline-formula><tex-math id="M4">\begin{document}${\varLambda _2} = 688\; {\text{μ}}{\rm m}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20181674_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="5-20181674_M4.png"/></alternatives></inline-formula>, 35-period by CO<sub>2</sub> laser in tow mode fiber (TMF steped-index fiber). The bandwidths of both LPFGs at a conversion efficiency of 10 dB are about 57 nm and 67 nm respectively, while the bandwidth of SLPFG is about 153 nm. The experimental results are in pretty good agreement with the theoretical analyses. In addition, the proposed superimposed structure can also be extended to the conversion of fundamental mode into other high-order core modes. By designing the period of two sub-gratings reasonably, a wide band rejection filter with arbitrary wavelength can be realized. Compared with the traditional mode converter, the converter has the advantages of broad bandwidth, high conversion efficiency and small size, which can be widely used in the mode division multiplexing system and optical communication.

Quantum repeater protocol in mixed single- and two-mode Tavis-Cummings models

In this paper we study the production of entanglement between two atoms which are far from each other. We consider a system including eight two-level atoms (1, 2, ⋯, 8) such that any atom with its adjacent atom is in an atomic Bell state, so that we have four separate pairs of maximally entangled states where . Our purpose is to produce entanglement between the atomic pair (1, 8), while these two distant atoms have no interaction. By performing the interaction between adjacent non-entangled atomic pairs (2, 3) as well as (6, 7), each pair with a two-mode quantized field, the entanglement is produced between atoms (1, 4) and (5, 8), respectively. Finally, by applying an appropriate Bell state measurement (BSM) on atoms (4, 5) or performing an interaction between them with a single-mode field (quantum electrodynamic: QED method), the qubit pair (1, 8) becomes entangled and so the quantum repeater is successfully achieved. This swapped entanglement is then quantified via concurrence measure and the effects of coupling coefficients and detuning on the concurrence and success probability are numerically investigated. The maxima of concurrence and success probability and the corresponding time periods have been decreased by increasing the detuning in asymmetric condition in the BSM method. Also, the effects of detuning, initial interaction time and coupling coefficient on the produced entanglement by the QED method are considered. Increasing (decreasing) of the detuning (interaction time) has a destructive effect on the swapped entanglement in asymmetric condition.

Moving Bragg grating solitons in a semilinear dual-core system with dispersive reflectivity

The existence, stability and collision dynamics of moving Bragg grating solitons in a semilinear dual-core system where one core has the Kerr nonlinearity and is equipped with a Bragg grating with dispersive reflectivity, and the other core is linear are investigated. It is found that moving soliton solutions exist as a continuous family of solutions in the upper and lower gaps of the system’s linear spectrum. The stability of the moving solitons are investigated by means of systematic numerical stability analysis, and the effect and interplay of various parameters on soliton stability are analyzed. We have also systematically investigated the characteristics of collisions of counter-propagating solitons. In-phase collisions can lead to a variety of outcomes such as passage of solitons through each other with increased, reduced or unchanged velocities, asymmetric separation of solitons, merger of solitons into a quiescent one, formation of three solitons (one quiescent and two moving ones) and destruction of both solitons. The outcome regions of in-phase collisions are identified in the plane of dispersive reflectivity versus frequency. The effects of coupling coefficient, relative group velocity in the linear core, soliton velocity and dispersive reflectivity and the initial phase difference on the outcomes of collisions are studied.

Estimation of the Bandwidth of Acceptable Crosstalk of Parallel Coupled Ring Resonator Add/Drop Filters

In this paper, a parallel coupled optical ring resonator filter is studied and the transfer function is derived using the signal flow graph (SFG) approach to identify the filter performance in terms of crosstalk suppression bandwidth and signal integrity. This paper proposes the use of the SFG (Mason's rule) approach to determine the filtering characteristics of parallel coupled ring resonators. A commercial electromagnetic simulator is used to validate the analytical model. The modeling of the parallel coupled ring resonator covers the analysis of the out-of-band rejection ratio, crosstalk suppression, loss effect, and the effect of coupling coefficients on the crosstalk bandwidth. The good agreement between analytical model results and simulation results suggests that using the derived analytical model provides an accurate starting point for design and analysis and, in doing this, provides a better insight into the signal integrity performance of the filter.

Proposal for an optical multicarrier generator based on single silicon micro-ring modulator

We propose an optical multicarrier generation technique using silicon micro-ring modulator (MRM) and analyze the scheme. Numerical studies have been done for three types MRMs having different power coupling coefficients. The proposed scheme is found to generate four optical carriers having 12.5GHz spacing. According to simulation, the maximum side-mode-suppression ratio (SMSR) of ~16.3dB with flatness of ~0.2dB is achieved by using this scheme. The minimum extinction ratio (ER) of the generated carriers is found to be more than 35dB. We also propose modulator driver circuit to generate RF signal, which is needed to generate multicarrier using MRM. The effect of coupling coefficient on the SMSR of the generated carriers is also investigated.

Spatial vector soliton in nonlocal nonlinear media with exponential-decay response

The propagation of two orthogonally polarized incoherent optical beams in strong nonlocal nonlinear media with exponential-decay response was investigated by a variational approach, and the analytical result was confirmed by numerical simulation. The evolution equations for the parameters of the two beams were obtained and a spatial vector soliton was found. The effects of coupling coefficient and birefringence on the propagation of the two beams were discussed. A soliton-like wave, which is different from the vector soliton, was discovered. Moreover, the phase shifts of the two beams are different under certain conditions and the propagation distance of generating π phase difference can be figured out. These theoretical result have the potential application to developing the logical devices or optical switching, which based on the principle of phase difference or polarization.

Phase Field Simulation of Dendrite Growth of Coupling Coefficient Effecting

The phase field coupling with the temperature distribution field is used to simulate the dendrite growth during isothermal solidification. The effects of coupling coefficient on the dendrite growth are studied. The results indicate that grain shape is hypertrophy dendritic crystal When the coupling coefficient is low. As coupling coefficient increases, the main branch of dendritic crystal become long and thin, and has the stable front interface. When the coupling coefficient is large, the dendrite growth becomes very complicated and the front interface of it is very unstable. Meanwhile, the temperature distribution field of main branch tip increases slowly first, then decreases; in addition to the main branch ,the temperature field increases monotonously.

Analytical Study on Characteristics of Dual Microring Resonators Combined with the Add-drop and All-pass Types

This paper presents an analytical study on characteristics of dual microring resonators combined with the add-drop and all-pass types, which can provide novel filtering and delaying characteristics. Analytical expressions of transmission spectra and normalized delays of the dual microring resonators are developed using the transfer matrix method. The effects of coupling coefficients and loss on both transmission spectra and delays are then investigated. The analytical study shows that two resonance peaks of transmission spectra are existent. Under lossless coupling, the resonance frequency of the transmission spectra increases as the ring-ring coupling coefficient increases. However, it is independent on the ring-bus coupling coefficient. The valley amplitude of the transmission spectra increases as the ring-bus coupling coefficient increases, which is also independent on the ring-ring coupling coefficient. Generally, three delay peaks are existent. The corresponding frequencies of delay peaks on either side of the centre frequency are partially coincident with the normalized resonance frequencies of transmission spectra. The normalized delays can develop from three delay peaks to two delay peaks or single delay peak under specified coupling coefficients and loss.

SPM Response of a Distributed coupling coefficient DFB-SOA All-Optical Flip-Flop

Deriving a dynamic model based on the coupled-mode and carrier rate equations, the effects of coupling coefficient and corrugation position on all-optical flip-flops (AOFF) we have analyzed in this paper. Also the self phase modulation (SPM) in the distributed coupling coefficient distributed feedback semiconductor optical amplifier (DCCDFB-SOA) has been implemented. Then the effects of SPM on the rise and fall times of the flip-flop DFB-SOA are investigated. It has been shown that the application of the optimized coupling coefficient and corrugation position improves the speed limitation in AOFF significantly. The transfer matrix method (TMM) time domain is utilized for the numerical simulations.

Effect of Coupling Coefficients on Self-Pulsation Characteristics in Multi-Section Distributed Feedback Lasers with Amplifying Optical Feedback

The self-pulsation characteristics of amplifying feedback lasers (AFLs) composed of a distributed feedback section, a phase tuning section, and an amplifier section for various coupling coefficients are investigated. AFLs with anti-phase gratings give wide operational ranges for stable pulsation compared to those with in-phase gratings and index gratings. The operational ranges for stable pulsation increase as the coupling strength increases and the value of the gain coupling coefficient of anti-phase grating increases.

Transmission characteristics of dual microring resonators coupled via 3×3 couplers

New types of dual microring resonators coupled via 3x3 couplers are proposed. By employing the transfer matrix method, a model for these four types is developed and analytical expressions for characterizing their transmissions are derived. The first two types show a coupled-resonator-induced-transparency-like transmission spectrum at the through port. The third type holds the same transmission spectrum, while the last type simultaneously realizes a first-order and a second-order filters at two drop ports. The effects of coupling coefficients on their transmission spectra are investigated in more detail. Moreover, the effects of loss are also discussed. These proposed types can be found applications in fields such as sensors and filters.