Ferrite resonance isolators in coaxial,strip, and rectangular waveguides with a dielectric

An analysis is given of ferrite resonance isolators in coaxial and strip lines and in a rectangular waveguide containing a dielectric. The analysis is based on numerical calculations (using a computer) using the results obtained in [1]. The results enable us to estimate the influence of the thickness of the dielectric, its permittivity, the ferromagnetic resonance line width and other parameters, upon the bandwidth of the system and upon the optimum magnetization ensuring the maximum isolation for the chosen system parameters and center frequency of the band. In this paper the terminology used is the same as in [1].     

Optical characteristics of bent dielectric rectangular waveguides

Bent rectangular waveguide characteristics are analysed using conformal transformation and four-layered waveguide approximation. Using this method the physical model is clear, the optical characteristic expressions given are uncomplicated and the computed result is in good agreement with the results of Marcatili and Marcuse.     

Characteristics of TE-modes in rectangular waveguides containing dielectric layers

The eigenequation of TE-modes in rectangular waveguides filled with arbitrary layer dielectrics is presented. As an example, we calculate the characteristics of a rectangular waveguide which is devided three regions by dielectrics. Using a Personal Computer the results can be got in several minutes, and the results agree with that of other authors very well. Some curves are given.     

Low radiation loss Y-junctions in planar dielectric optical waveguides

A simple structure is proposed to reduce radiation losses of Y-junctions in planar optical waveguides by decreasing refractive indices near the branching regions. The losses of the properly designed Y-junctions can be reduced by around an order of magnitude compared with those of conventional ones when the branching angles are large.     

Reflectionless evanescent-wave amplification by two dielectric planar waveguides

Utilizing the underlying physics of evanescent-wave amplification by a negative-refractive-index slab, it is shown that evanescent waves with specific spatial frequencies can also be amplified without any reflection simply by two dielectric planar waveguides. The simple configuration allows one to take advantage of the high resolution limit of a high-refractive-index material without contact with the object.     

Symmetric electromagnetic waves in a dielectric coaxial line

On the basis of a solution of the Maxwell equations the configuration of electromagnetic fields of symmetric types of oscillations in a dielectric coaxial line is found. The expressions for power density for both symmetric and hybrid waves are obtained. The direction of power density coincides with the axis of various axial symmetric dielectric structures. The dependences of phase speeds of electric and magnetic waves on frequencies of radiation are presented. The frequency range in which only the lowest index symmetric waves propagate is found. At frequencies higher than critical, discrete symmetric modes of oscillation exist. The energy is transmitted mainly inside the dielectric rod, and the power density at the axis is equal to zero.     

Free space radiation mode analysis of rectangular dielectric waveguides

The free space radiation mode (FSRM) method is used to provide a new closed-form transcendental equation for the scalar mode propagation constant of a uniformly buried rectangular dielectric waveguide. Results are readily and rapidly obtained and are shown to be very accurate over the range of practical interest.     

Exact transcendental equation for scalar modes of rectangular dielectric waveguides

Conclusion A Fourier operator method has been used to derive for the first time an exact closed-form eigenvalue equation for the scalar mode propagation constants of a buried rectangular dielectric waveguide. The new method has been implemented and the results used to determine the accuracy of the scalar finite-difference approach. It is hoped that the exact results obtained here may assist in the validation of the accuracy of the other numerical and semi-analytical methods.     

Reflectionless evanescent-wave amplification by two dielectric planar waveguides: erratum

In a previous Letter [Tsang and Psaltis, Opt. Lett.31, 2741 (2006)], we assert that the total reflection coefficient of two dielectric slabs goes to zero in the limit of single-waveguide resonance. A more careful derivation shows that this is not the case. The correct condition in which reflectionless evanescent-wave amplification can be achieved by two dielectric planar waveguides is derived in this Erratum.     

Rigorous analysis of optical forces between two dielectric planar waveguides immersed in dielectric fluid media

This work presents a rigorous analysis of optical forces between planar waveguides immersed in an arbitrary background medium. This approach exploits the Minkowski stress tensor formulation, which is compared with a normalized version of the dispersion relation method, showing excellent results agreement for different dielectric fluid media. Due to slot‐waveguide effect, optical forces from TM modes are more sensitive to changes in the fluid refractive index than the TE counterparts. Furthermore, the repulsive optical force from the antisymmetric TM1 mode becomes stronger for higher refractive indexes, whereas the attractive force of the symmetric TM0 mode becomes weaker. The methodology and results presented in this work provide a rigorous analysis of nano‐optomechanical devices actuated by optical forces in a broad range of materials and applications. Therefore, this study may impact areas of light‐induced interactions presenting novel optofluidic and optomechanical functionalities, thus finding applications in nanoscale transport, sensing and manipulation.

     

An exact numerical analysis of coupled planar electron waveguides with asymmetric rectangular potential profiles

An exact numerical analysis is given of electron waves in a pair of coupled semiconductor heterojunction electron waveguides modelled by a rectangular potential distribution. The waveguide lengths required for electron current transfer between the guides agree asymptotically with estimates from Yariv's coupled mode theory and are usefully more accurate. Moreover the electron wave coupling due to an ideal launcher can be worked out, leading to estimates of the off/on current ratio occurring in the waveguides when regarded as an ultrafast switch. For a Poisson probability distribution of the number of electrons N making up a bit-pulse, we have calculated the minimum average N, dependent upon , which would be required to keep the switching bit-error rate below prescribed limits. Pulse rise times and switching delays are derived from the explicit forms for the longitudinal electron wave group velocity. Combining the bit-error and switching-time calculations leads to estimates of the waveguide current densities which would be required in practice. Some normalized sets of curves relating to our analysis are given and used to predict the performance of particular examples of recently proposed AlGaAs/GaAs heterojunction electron waveguide switch/couplers.     

A comparison of approximate methods for calculation of rectangular dielectric waveguides

Physical Problems Institute, Academy of Sciences of the USSR. Translated from Isvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 1, pp. 93–97, January, 1990.     

Theory of resonance tunnel coupling of lossy dielectric waveguides

Physics Institute, Estonian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 8, pp. 970–975, August, 1990.     

Low-loss, compact waveguiding with TE mode in metal/dielectric waveguides for planar lightwave circuit

We propose a low-loss metal/dielectric waveguide for compact planar lightwave circuit. The basic waveguide structure is a metal-defined high-index-contrast strip waveguide based on silicon/silica. As the guide is designed for TE single mode waveguiding, extremely low propagation loss (e.g. <0.04 dB/cm), very low bend loss (e.g. 0.0043 dB/90°-turn) and small waveguide pitch of zero-crosstalk are theoretically achievable, and can be further improved by compromising with component size and density. Examples of multi-bends and device integration are demonstrated with numerical simulations. The proposal is compatible with silicon technology and appealing for development of silicon-based planar lightwave circuit.     

同轴线-矩形波导结散射特性的数值分析

 提出了一种数值分析同轴线-矩形波导结散射特性的模式匹配方法。采用同轴线和矩形波导的本征模函数表示电磁场分量,通过同轴线-矩形波导结截面横向场分量匹配获得波导结的散射参数,引入电场模式匹配矩阵的解析形式提高了计算效率。给出了基于模式匹配法数值仿真的各种同轴线-矩形波导结散射特性及仿真结果分析,并与3维全电磁波分析软件HFSS的仿真结果进行了比较,二者非常吻合。模式匹配法计算效率高,能广泛应用于微波毫米波元器件及系统结构的设计与优化。     

Improved inverse WKB procedure to reconstruct refractive index profiles of dielectric planar waveguides

A new method to reconstruct smooth refractive-index profiles from measured effective indices is presented. The profile form near the surface and its approach towards the bulk value are explicitely taken into account. Well behaved profiles such as Gaussian or exponential can be reconstructed within experimental accuracy from three modes only, and even two modes may provide useful information. The method is tested for numerical stability.     

Comparative study of asymmetric versus symmetric planar slab dielectric optical waveguides

In this paper we have studied the asymmetric versus symmetric planar waveguide in terms of their usefulness in optical fiber communication systems. We have explored the thin waveguide versus thick waveguide first. Later on usefulness of asymmetric versus symmetric waveguide is carried out to target for WDM optical network application. All kinds of optical network components are fabricated on Si substrate with the point of view of their application. Here asymmetric planar structure may be more useful compared to symmetric waveguide in terms of their non-uniform power confinement properties. However, the symmetric waveguide structure may be more useful for their high power confinement properties. It is well known that the thin symmetric waveguide supports at least one mode. However the thick waveguide may support many even as well as odd modes. We study the power confinement properties for symmetric as well as asymmetric waveguide structure. We conclude that higher order modes show the nonlinear power variations. Mode field profile for various cases is discussed as well. Comparative study between asymmetric versus symmetric waveguide has a lot of significance in optical network area. It has been shown through analysis that in asymmetric waveguide, the power flows more through film region in the case of fundamental mode. Power confinement properties for asymmetric waveguide versus symmetric waveguide have been studied.