Multilayer Dielectric Waveguide Research Articles

A fast convergent solution of wave propagation for multilayer inhomogeneous cylindrical dielectric waveguides using a semianalytical method

Abstract This paper presents an accurate and efficient semianalytical method based on the Galerkin procedure for solving electromagnetic wave propagation problems in multilayer inhomogeneous cylindrical dielectric waveguides. The method represents the field in each inhomogeneous layer by a linear combination of eigenfunctions with unknown coefficients, which are expressed using the inner products of a series of basis functions, following the Galerkin procedure. The continuity of the field and its radial derivative is enforced at the interface between adjacent layers. By applying this procedure to all inhomogeneous layers, the Helmholtz equations are transformed into linear algebraic equations with expanded coefficients in matrix form, allowing the complicated wave propagation problem in a multilayer inhomogeneous waveguide to be solved as a matrix eigenvalue problem. The method is validated by providing detailed propagation characteristics for various multilayer inhomogeneous cylinders with different permittivity profiles. The accuracy and efficiency of the proposed method are demonstrated through comparisons with results obtained using other numerical techniques.

All-dielectric scale invariant waveguide

Total internal reflection (TIR) governs the guiding mechanisms of almost all dielectric waveguides and therefore constrains most of the light in the material with the highest refractive index. The few options available to access the properties of lower-index materials include designs that are either lossy, periodic, exhibit limited optical bandwidth or are restricted to subwavelength modal volumes. Here, we propose and demonstrate a guiding mechanism that leverages symmetry in multilayer dielectric waveguides as well as evanescent fields to strongly confine light in low-index materials. The proposed waveguide structures exhibit unusual light properties, such as uniform field distribution with a non-Gaussian spatial profile and scale invariance of the optical mode. This guiding mechanism is general and can be further extended to various optical structures, employed for different polarizations, and in different spectral regions. Therefore, our results can have huge implications for integrated photonics and related technologies.

Numerical analysis of low-RI WGM resonators excited by a periodically arranged multilayer dielectric planar waveguide

In the applications of whispering gallery mode (WGM) resonators, especially those with low refractive indices (RIs), optical excitation is always a critical issue due to the lack of suitable and matching waveguide materials. The Bloch surface wave (BSW) can facilitate achieving an effective coupling, resulting from its field distribution extending a large portion of its mode energy around the external surface and its easy adjustment of the effective refractive index. In this paper, a BSW waveguide platform for adaptive excitation of spherical WGM resonators is proposed, designed, and numerically analyzed. The simulation results show that the WGM resonator stimulated by BSW exhibits a resonance depth (RD) as large as ∼98% and a high total quality factor Qtotal∼3.13×104 which is in the same order of magnitude as its intrinsic value Qintrinsic of 5.8×104. Moreover, less limited by its constitutive materials, this BSW-WGM platform is robust and especially suitable for fully integrated applications.

Analytical and Experimental Study of Multilayer Dielectric Rod Waveguides

This article presents a comprehensive study of the design and performance of a multilayer dielectric rod waveguide (MDRW) with a rectangular cross section. The design is comprised of a high permittivity core encased by a low permittivity cladding. A mathematical model is proposed to predict the fundamental mode cutoff frequency in terms of the core dimensions and the core and cladding permittivity. The model is useful for design purposes and it offers an excellent match to full-wave electromagnetic (EM) simulation results. The MDRW performance is measured for the extended Ku-band (10-18 GHz) considering straight and bent waveguides with different radius of curvatures. The particular multilayer configuration shows a 16.7% and 24% extension of the 1 dB low-band cutoff frequency for a 10×10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 20×20 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> cladding area, respectively, when compared to a single layer dielectric rod waveguide (DRW) design of the same core dimensions. MDRW bends also exhibit a significant reduction of the 1 dB low-band cutoff frequency from 20% to 40% when compared to single-layer designs, for the different radius of curvature bends.

Generation of THz radiation by sequence of ring beams in multilayer dielectric waveguide

In this paper, we describe a new type of a THz radiation source in a multilayer dielectric waveguide based on the Vavilov-Cerenkov radiation created by a sequence of electron ring beams. We present parameters of the sequence needed for generation of TM03 with frequency of 531.2 GHz in result radiation and results of beam dynamics calculation. Also, we discuss the degree of monochromaticity and spectrum of the THz radiation.

Wakefield acceleration in multilayer dielectric waveguide with usage of ring beam

In this paper, we simulated the process of wakefield acceleration of electron Gaussian bunch by electron ring beam. The beam dynamics of ring uniform is discussed in detail. Calculation results show that wakefield accelerating scheme is more effective compared to the scheme with one-layer dielectric waveguide excited by gaussian bunch.

Matrix method for two-dimensional waveguide mode solution

In this paper, we show that the transfer matrix theory of multilayer optics can be used to solve the modes of any two-dimensional (2D) waveguide for their effective indices and field distributions. A 2D waveguide, even composed of numerous layers, is essentially a multilayer stack and the transmission through the stack can be analysed using the transfer matrix theory. The result is a transfer matrix with four complex value elements, namely A, B, C and D. The effective index of a guided mode satisfies two conditions: (1) evanescent waves exist simultaneously in the first (cladding) layer and last (substrate) layer, and (2) the complex element D vanishes. For a given mode, the field distribution in the waveguide is the result of a ‘folded’ plane wave. In each layer, there is only propagation and absorption; at each boundary, only reflection and refraction occur, which can be calculated according to the Fresnel equations. As examples, we show that this method can be used to solve modes supported by the multilayer step-index dielectric waveguide, slot waveguide, gradient-index waveguide and various plasmonic waveguides. The results indicate the transfer matrix method is effective for 2D waveguide mode solution in general.

Purcell-enhancement of the radiative PL decay in perylenediimides by coupling with silver nanoparticles into waveguide modes

In this work, an interesting approach to enhance the coupling between excitons and plasmons is proposed by integrating highly luminescent perylenediimides (PDIs) and Ag metal nanoparticles (MNPs) in the core of a multilayer dielectric waveguide. The combination of the weak plasmonic coupling and the high scattering of MNPs gives rise to a significant improvement of the PDI photoluminescence and Purcell factor (PF) in forward-scattering geometry. Furthermore, when the PDI-MNP system is used as the core of a multilayer waveguide, a Purcell factor enhancement larger than 10 is observed, which is explained by an increase in the exciton-plasmon coupling under the light confinement in the waveguiding structure as compared to a single layer of PDI emitters.

Simulation of Temperature Dependences of Emission Characteristics of Nano-Layer Injection Lasers Based on Symmetric Heterostructures

The exact problem of electromagnetic wave propagation in a multilayer nanostructure with complex values of dielectric permittivity is solved. The contribution to the refractive index of an additive to the dielectric constant connected with the injected carriers is taken into account. Within the framework of this problem, it is shown that an anomalous temperature dependence of the threshold current of injection lasers based on nanoheterostructures is related to the anti-waveguide action of injected carriers. A quantum-well heterostructure based on InGaAs/AlGaAs/GaAs nanosystems used for fabrication of 0.94-1.14 μm lasers is considered. The applied techniques and approaches are also acceptable for the optimization of multilayer nanostructures based on other solid solutions. As an optical model of the active region of injection lasers based on nanostructures, a planar multilayer dielectric waveguide with complex values of dielectric permittivity in the layers is considered. It is shown that with decreasing thickness of the active region of injection lasers, the dependence of the mode gain on the local gain is essentially sublinear. The reason for this is the antiwaveguide action of electrons. The results of calculations of the temperature dependence of the threshold current of injection lasers indicate the presence of a critical point Tc, at which a sharp decrease in the characteristic temperature occurs. The performed calculations and optimization of the temperature dependence of emission characteristics of injection lasers based on nanostructures show that the anomalous behavior of the temperature dependence of the threshold current is also associated with the weakening of the waveguide properties of theirs active region.

Methodology for Coupling and Interference Prediction in Integrated-Circuit Substrates

This paper presents a methodology to evaluate different integrated-circuit substrate technology options in terms of interference coupling. It is based on the electromagnetic characterization of the different substrate configurations as radial multilayered dielectric lossy open waveguides and the selection of the propagation modes that effectively contribute to substrate coupling. In addition, attenuation patterns are obtained for different technologies, doping profiles, frequencies, and interference mechanisms in order to provide a tool for early interference prediction, electromagnetic compatibility performance evaluation and floorplan strategy definition.

On generation of electromagnetic waves in the terahertz frequency range in a multilayered open dielectric waveguide

Abstract We show that it is possible to produce terahertz wave generation in an open waveguide, which includes a multilayer dielectric plate. The plate consists of two dielectric layers with a corrugated interface. Electrons, drifting in the potential well, interact with the non-uniform electric field which is induced near the dielectric interface by the natural wave of the waveguide. The corrugated period and parameters of the electronic system are chosen in order to ensure the most effective interaction of electrons with a wave. Generation of electromagnetic waves is achieved by converting the electronsʼ energy into the electromagnetic wave energy.

Variational Formulation for Guided and Leaky Modes in Multilayer Dielectric Waveguides

Variational Formulation for Guided and Leaky Modes in Multilayer Dielectric Waveguides

LM modes in semiconductor-dielectric plane-layered waveguide with dissipative and active layers

With the use of the iteration method and bilinear functional based on two-dimensional volume integral equation, LM modes existing in a plane-layered dielectric waveguide and quasi-LM modes existing in a multilayered rectangular dielectric waveguide are studied. The semiconductor layers are described as a homogeneous single-component dissipative plasma that can exhibit negative conductivity owing to external electric field. The results obtained for a homogeneous single-layer rectangular waveguide are compared to the results obtained with a model of a planar single-layer waveguide. Structures with passive and active semiconductor-plasma layers are investigated. It is shown that amplification is possible at frequencies above the cutoff frequency and that the dispersion laws below the cutoff are complicated.

Solving dielectric and plasmonic waveguide dispersion relations on a pocket calculator

We present a robust iterative technique for solving complex transcendental dispersion equations routinely encountered in integrated optics. Our method especially befits the multilayer dielectric and plasmonic waveguides forming the basis structures for a host of contemporary nanophotonic devices. The solution algorithm ports seamlessly from the real to the complex domain--i.e., no extra complexity results when dealing with leaky structures or those with material/metal loss. Unlike several existing numerical approaches, our algorithm exhibits markedly-reduced sensitivity to the initial guess and allows for straightforward implementation on a pocket calculator.

Determination of wave propagation properties for multilayered dielectric waveguide by semivectorial beam propagation method with Douglas scheme

AbstractAn improved parabolic‐equation‐based numerical method with Douglas scheme is developed for modeling the new 3D multilayered dielectric transmission waveguides. Unlike the traditional one, such waveguides are constructed by putting the multilayered dielectric cladding with step indices property on a silicon substrate. The propagation properties of widely used polarization‐maintaining waveguides and antiresonant reflecting dielectric waveguide are investigated by this method as examples. The discussion on the numerical dispersion and radiation loss property is also included to validate this improved beam propagation method (or BPM). © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2521–2524, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23725

Pure currents in foliated waveguides

We give an explicit characterization of obliquely propagating electric modes within a multilayered planar dielectric waveguide of cross-section [0, 1]. This foliated strip, with fixed metallic boundaries at 0 and 1, consists of an integer number N of periodic cells of thickness η = 1/N. We are interested in the high-frequency asymptotic analysis of its spectrum. For this, we rescale the wavelength as η and derive, using a transfer matrix formalism, that for vanishing η the limit spectrum consists of two parts. The first part is a Bloch (or band) spectrum associated with a family of operators acting on Floquet–Bloch eigenfunctions defined on the real line. The second part is a boundary layer spectrum associated with an operator acting on square integrable eigensolutions defined on the positive real line [0,+∞) and satisfying a Neumann condition at 0. This latter part is further characterized via a spectral problem on [0, 1] which is supplied with Neumann conditions at both ends. Eventually, we illustrate our discussion by numerical results derived from this auxiliary spectral problem. Moreover, after a suitable rescaling of the field, we prove that the total electromagnetic energy is entirely located on either boundary of the structure. Finally, in the case of transverse propagation, we apply our results to antiplane shear waves propagating within a foliated acoustic waveguide, whose freely vibrating walls at 0 and 1 are shown to support surface waves.

Modeling and Analysis of a Multilayer Dielectric Slab Waveguide With Applications in Edge-Coupled Terahertz Photomixer Sources

The waveguiding properties of a multilayer dielectric slab waveguide structure with applications in edge-coupled terahertz photomixer sources are studied. The structure guides two interfering laser beams, which their central frequency difference falls into the terahertz spectrum. The top layer of the dielectric waveguide structure is made of an ultrafast photoabsorbing material, wherein the power of the guided modes are being absorbed and converted into a terahertz signal. The optical field and power distributions inside the waveguide structure are studied for different physical parameters of the dielectric layers. The absorbed optical intensity and the generated terahertz photocurrent and terahertz power inside the photoabsorbing layer are calculated

A Low Loss Multi-Layer Dielectric Waveguide Filter for 60-GHz System-on-Package Applications

For V-band applications, this paper presents a fully embedded multi-layer dielectric waveguide filter (DWGF) with very low insertion loss and small size, which does not need any more assemblies such as flip-chip bonding and bond wires. The top and bottom plane are grounded, and therefore, although we make a metal housing, there will be no resonance occurrences. Especially, the proposed structure is very suitable for MMICs interconnection because the in/output pads consist of conductor backed co-planar waveguide (CBCPW). The filter is formed incorporating metallized through holes in low temperature co-fired ceramic (LTCC) substrates with relative dielectric constant of 7.05. The total volume of the filter including transitions is 4.5 mm × 2.65 mm × 0.4 mm. A fabricated DWGF with four transitions shows an insertion loss and a return loss of 2.95 dB and less than 15 dB at the center frequency of 62.17 GHz, respectively. According to the authors' knowledge, the proposed filter shows the lowest insertion loss among the embedded multi-layer millimeter-wave filters ever reported for 60 GHz applications.

High-performance low-cost phase-shifter design based on ferroelectric materials technology

A novel approach to ferroelectric phase-shifter design using BaxSr1-xTiO3 (BSTO) films in a multilayer dielectric coplanar waveguide structure is described. By including a low-loss dielectric layer (SiO2) between the coplanar waveguide conductors and a layer of ferroelectric materials, significant reduction in insertion loss can be achieved in conjunction with a threefold increase in figure of merit (°/dB).

Dynamic modifications to the plasmon resonance of a metallic nanoparticle coupled to a planar waveguide: beyond the point-dipole limit

We show that the effects of a nearby surface on the plasmon resonance of a metallic nanoparticle of finite size can be modeled by expanding the secondary local field at the particle position in terms of an integral expansion of elementary waves that has the form of a Sommerfeld integral. In this way it is a straightforward matter to apply the Fresnel reflection coefficients of the surface to the secondary field and thus derive a corrected expression for the effective polarizability of the particle. We apply our theoretical result to particles near metal-clad and multilayer-dielectric waveguides and show that a substantial amount of the light scattered by a particle can propagate radially outward confined to the guided modes of the substrate.