Kind Of Coupler Research Articles

Cubic–quartic solitons in couplers with optical metamaterials having triple-power law nonlinearity (sequel to polynomial law)

This paper retrieves soliton solutions to couplers in optical metamaterials with triple-power law of nonlinear refractive index and is thus a sequel to previously reported results with polynomial law of nonlinear refractive index. The enhanced Kudryashov’s scheme made this possible. Two kinds of couplers are addressed, namely twin-core and multiple-core. A full spectrum of soliton solutions are displayed.

Broadband high-efficiency triple-tip spot size converter for edge coupling with improved polarization insensitivity

Fiber-to-chip couplers are an essential part of the interfaces to integrated photonic devices, and high coupling efficiency over a broad wavelength range is preferred for most applications. Furthermore, couplers with low polarization dependence are also of great practical significance. While tapered waveguide couplers have been applied to overcome the mode mismatch between waveguides and fibers, the inherent geometric asymmetry of high-index-contrast waveguides, especially for those with a thick core layer, leads to polarization dependence in their performance. Here a triple-tip spot size converter as an edge coupler is proposed to improve the polarization insensitivity and coupling efficiency over a broadband range for either thick or thin waveguides. For both TE and TM polarization, it is shown that our design can have below 1 dB coupling loss over a 600 nm window around 1550 nm wavelength for Si3N4 waveguides of typical core thicknesses. Meanwhile, this kind of coupler also shows better fabrication and assembly tolerance than the traditional single-tip spot size converter (inverse taper coupler). Our proposed device can be easily fabricated in simple fabrication processes compared to other designs and have good compatibility with the standard complementary metal-oxide–semiconductor processes.

A Narrow-Rail Three-Phase Magnetic Coupler With Uniform Output Power for EV Dynamic Wireless Charging

For the EV dynamic wireless charging system, the conventional single-phase magnetic couplers with alternately arranged magnetic poles, such as I-type, S-type, and N-type, have both the advantage of narrow power supply rail and the disadvantage of large output power fluctuation. Although the conventional three-phase meander-type magnetic coupler uses the traveling wave magnetic field to ensure uniform output, a wide transmitter is required in order to provide a large air gap. This article proposes a narrow-rail three-phase magnetic coupler, which realizes the advantages of the above two kinds of couplers by integrating the narrow rail with uniform output power in one coupler. The magnetic field distribution and the working principle of the proposed coupler are illustrated and the receiver structure and the transmitter coil's winding method are optimized. Moreover, the effect of the interphase mutual inductance between different phases in transmitter coils on the system is analyzed. Finally, an experimental prototype was built for the verification. The experimental results showed that the fluctuation of output voltage was within ±2.5% during the dynamic charging process.

A class of coupled-line trans-directional coupler with independent or simultaneous tuned frequency, coupling coefficient and phase difference

The paper reports on the design of coupled-line trans-directional (CL-TRD) coupler with independent or simultaneous tuned frequency, coupling coefficient and phase difference (PD). Based on the proposed structure, four kinds of couplers are exhibited, including a phase-tuned coupler with arbitrary frequency and coupling, a frequency-tuned coupler with arbitrary coupling and non-standard phase, a coupling-tuned coupler with arbitrary frequency and non-standard phase, a simultaneous frequency-, coupling- and phase-tuned coupler. In the section of theoretical analysis, rigorous closed-form design equations are derived using the even-odd mode analysis. For verification, four prototypes are designed, fabricated and measured. Three of them are couplers with independent frequency, coupling or phase tuned. The designed 3-dB frequency-tuned coupler exhibits a frequency tuning range of 58.8% with a PD of 60°. The coupling-tuned coupler shows a tuning range of 3–15 dB with a PD of 70°. The designed phase-tuned CL-TRD coupler can provide a PD from 45° to 135°. Finally, a coupler with simultaneously frequency-, coupling- and phase-tunable was implemented. It has a wide frequency tuning range from 1.2 GHz to 2 GHz with a tunable coupling from 3 dB to 15 dB, and a tunable PD from 45° to 135°.

Dramatic enhancement of interfacial thermal transport by mass-graded and coupling-graded materials

With the dimension of materials shrinking into nanoscale, there has been growing interest in the Kapitza resistance which inhibits overall thermal transport. In this work, using the non-equilibrium Green's function method, we systematically investigate the optimized interfacial couplers with various gradient materials for phonon transport across one-dimensional atomic hetero-junction models. Relative to the optimized homogenous couplers, the mass-graded or coupling-graded structures are found to be applicable to improve the interfacial thermal conductance of two lead materials with both mismatched impedance and mismatched cutoff frequencies. For the couplers with both geometric graded mass and geometric graded coupling, the interfacial thermal conductance can be maximum enhanced (nearly up to sixfold enhancement on interfacial thermal conductance compared to the optimized homogenous case). The underlying mechanism of phonon transport enhancement by the optimized coupler is investigated by the phonon transmission coefficient: on the one hand, this kind of coupler is able to maximally suppress the destructive interference for transmitted phonon waves; on the other hand, the constructive interference for the transmitted phonon is also largely improved. Our findings may offer guidance for advanced thermal interface materials design.

Study of coupling optics involving graded index fiber excitation via upside down tapered parabolic microlens on the fiber tip

Based on the prescribed ABCD matrix for the transmission of paraxial rays, we analyze theoretically laser diode to single mode graded index fiber excitation via an upside-down tapered parabolic microlens on the fiber tip. In this context, we use some typical step, parabolic and triangular index fibers. The ABCD transformation matrices for upside down tapered parabolic microlens on the tips of step-index, triangular-index and parabolic-index fibers are employed in our analysis. In this formalism, we employ Gaussian field distributions for both the source and the fiber. In our study, we use here two different laser diodes emitting wavelengths 1.3 μm and 1.5 μm respectively. The execution of the prescribed formalism requires little computation. Such formalism is expected to generate tremendous interest for study of coupling optics related to such kind of coupler.

A Novel Planar Impedance-Transforming Tight-Coupling Coupler and Its Applications to Microstrip Baluns

A novel impedance-transforming coupled-line coupler with strong coupling coefficient is proposed in this paper. Its analytical design methodology and applications to microstrip baluns are presented. For demonstration purposes, four numerical examples of this proposed impedance-transforming coupler with different terminated impedances are given. The calculated results show that this proposed coupler not only matches two different groups of terminated impedances but also covers the total power-dividing ratio range from 0 dB to infinite value. The measured results of the fabricated coupler verify the proposed design approach. Finally, this kind of coupler is used to construct a novel planar microstrip balun. This proposed balun has many advantages including planar structure without any via holes, strong coupled lines, and wide operation bandwidth. The experimental results of this proposed balun operating at approximately 2 GHz demonstrated these proposed ideas.

Parameters Survey and Experiment on Steel Scaffold Components

Ten construction sites are chosen as survey places, and several parameters for scaffold designing are collected, such as the wall thickness of steel tube, the weight of three kinds of couplers, the working tighten-moment on belts of couplers. Corresponding to different tighten-moment of the right angle coupler and anti-slipping tests are carried out. Reliability of 97% and wall thickness of 2.7mm should be considered in scaffold designing only about 10% of the practical used couplers comply with the National Code. The working tighten-moment of couplers should be 40 ～ 50N • m, which is up to the load bearing capacity of coupler.

数值模拟在非对称双芯光子晶体光纤耦合器教学中的应用

By means of numerical simulation analysis of asymmetric dual-core photonic crystal fiber coupler,it is shown that this kind of coupler can neglect the effect of polarization property due to approximate coupling strength of two different coupling modes in two different polarization directions.Meanwhile,at a certain splitting ratio,the coupler with different wavelength response can produce wideband dual-core coupler with different splitting ratio,and the properties such as bandwidth,splitting ratio inaccuracy,coupling length can be greatly improved compared to the usual wideband fiber coupler.It can provide theoretical support for designing wideband asymmetric dual-core photonic crystal fiber coupler.

Modulation instability in nonlinear oppositely directed coupler with a negative-index metamaterial channel

The nonlinear optical coupler with a negative-index metamaterial (NIM) channel is different from a conventional one, mainly in that the former has an effective feedback mechanism due to the opposite directionality of the phase velocities in the two channels. In this paper, we study modulation instability (MI) in this new kind of couplers, trying to identify the different MI properties from those in conventional couplers. It is found that MI in the nonlinear optical coupler with a NIM channel is significantly influenced by the ratio of the forward- to backward-propagating wave's power and the nonlinear parameters. And the threshold condition for the ratio and input power can exist only in the normal dispersion regime where the ratio is positive. In addition, it is shown that MI occurs only for finite values of input power when the NIM channel is self-defocusing nonlinear material and another channel is self-focusing nonlinear material in the anomalous dispersion regime. Further, increasing input power may suppress the MI, quite different from the MI in the conventional couplers. For the conventional one, the increase of input power generally promotes the occurrence of MI. These findings suggest that the controllability of NIMs provides more ways to manipulate MI and soliton in couplers with NIM channels.

Theoretical Study on Phase Locking of Arrays of Mutually-Injected Fiber Lasers

Phase locking of arrays of mutually-injected fiber lasers is investigated theoretically. The phase-locked states of this array are analytically discussed. It is revealed that phase locking of this array is affected by the transfer characteristic of the coupler used for mutual injection. Arrays fabricated with two kinds of couplers (i.e., 1 × 3 coupler and the compound coupler built with two 1 × 2 couplers) are studied. It is found that the compound coupler is more suitable for phase locking of the array. The relationship between the phase-locked states and the number of elementary lasers of the array is also studied.

DISPERSION-MANAGED SOLITONS IN OPTICAL COUPLERS

The soliton perturbation theory is employed to study chirped solitons that propagate through optical couplers and is governed by the dispersion-managed nonlinear Schrödinger's equation. Here, in this paper, we have considered both kinds of couplers namely twin-core as well as the multiple-core type. In either case, both Gaussian and super-Gaussian solitons are taken into account.

High-efficiency light coupling in a submicrometric silicon-on-insulator waveguide

Light coupling into a sub-micrometer-thick waveguide is usually done through a grating coupler. Coupling efficiency is strongly enhanced by addition of a mirror above the grating. This new kind of coupler can be designed to achieve efficiencies as great as 80%. Numerical calculations for a high-angular-spread Gaussian incident beam are compared with experimental results obtained for a standard silicon-on-insulator waveguide.

Propagation constants and coupling properties of coupled trapped image waveguide

The odd and even mode propagation constants of uniformly coupled trapped image waveguides are calculated by using the methods of the effective dielectric constant and surface impedance matching. Theoretical characteristics of a coupler made of coupled trapped image waveguides are analyzed and they can be used as a foundation for the design of this kind of coupler.