Analysis Of Planar Waveguides Research Articles

Analysis of planar waveguides with a thin overlayer and nonlinear cladding

The aim of this paper is to analyse a planar optical waveguide with Kerr-type nonlinear cladding and a thin linear overlayer separating the cladding and the guiding core. The results of numerical calculations show that the bistable behaviour of the nonlinear waveguides can be easily controlled by changing the parameters of this additional layer. The analysis is based on the self-consistent iteration procedure which provides relevant dispersion characteristics limited to physically stable solutions.

Modeling of planar waveguides with anisotropic layers of variable thickness by the method of lines

A new algorithm for the analysis of planar waveguides for optical frequencies with anisotropic layers of nonconstant thicknesses is proposed and substantiated. This algorithm is based on the method of lines with discretization lines of various length. Impedance/admittance transformation formulas between the interfaces of the layers are developed with the help of the generalized transmission line (GTL) equations. The materials are assumed to be biaxial or specific anisotropic. The proposed algorithm is verified by numerical results.

Analysis of planar waveguides with index discontinuity or index slope discontinuity

In this paper, we propose a novel analytic transfer matrix method (ATMM) to the analysis of planar waveguides with index discontinuity or index slope discontinuity, for the cases when the conventional WKB method is no longer valid. We also analyze the physical insight of the approximations in WKB theory, and according to our research, the phase shift at the turning point is not π/2, but exactly π. Test calculations are done for an index profile with a known solution and the comparison shows that our method gives extremely accurate propagation constant.

Near-field characterization of thin planar optical waveguides

A detailed near-field analysis of planar waveguides supporting two modes has been carried out. Theoretical calculations for both step- and gradedindex profiles, have shown the near-field features produced by interference of the two mode wavefunctions, which depend on their phase difference and intensity ratio. Theoretical results have been experimentally confirmed by performing an independent control of the two last magnitudes during the measurements. Fitting the calculated near-field intensity distribution to the measured one, the index profile of the waveguide has been reconstructed. The profile parameters differ by less than 5% from those obtained with the m-line method. Theoretical and experimental single mode analysis, also included for comparison, result in less accurate parameters showing index jump deviations, with respect to the m-line method, of the order of 10%.

Planar waveguide analysis by the spectral index method: II. Multiple layers, optical gain and loss

The most general form of the spectral index method is presented for the analysis of multiple-layered rib and related semiconductor waveguide structures where the ribs have vertical sidewalls and are surrounded by air. The model allows for the presence of loss or gain in any layer and the generalization of the method to such complex problems is described. A detailed account is provided on how to set up the transcendental equation to solve problems for single ribs, and both symmetric and asymmetric couplers. Finally, a polarization filter in the form of an asymmetric coupler with one of its ribs capped with metal is analysed numerically to illustrate the technique for a realistic design problem.

Planar waveguide analysis by the spectral index method. I: Rib and uniformly buried waveguides

The scope of the spectral index method for solving general planar waveguiding problems is analysed by first showing how simple it is to set up a closed-form transcendental equation whose solution is very accurate; the solution is so fast that the method can be used as a subroutine, making it possible to solve many two-dimensional problems fully, even for coupled rib waveguides, without using effective index approximations. The method is then extended to the uniformly buried waveguide of rectangular cross-section, and the corresponding coupler, thereby unifying the effective index, transverse resonance and spectral index methods for the first time, and giving an asymptotic expression for the coupling length without using overlap integrals. Finally, sample numerical results and optical field profiles are given for the rib waveguide and rib waveguide coupler.

Analysis of planar waveguides formed by nonuniform nonlinearity

A planar waveguide containing a nonlinear film whose thickness varies in the transverse direction can be used to simulate propagation in a one (transverse)-dimensional medium with constant refractive index but a spatially varying nonlinearity. This idea is illustrated by finding the steady-state solutions for several examples.

Erratum: Analysis of planar waveguides formed by nonuniform nonlinearity

Erratum: Analysis of planar waveguides formed by nonuniform nonlinearity

Rugorous analysis of planar waveguides with two-dimensionally periodic layer

Rigorous analysis of planar waveguides with two-dimensionally periodic (2DP) layer is presented. Characteristic solutions in periodic layer are exactly represented by a double Fourier series known as the Floquet solutions. The vector amplitudes of space harmonics are proved to be governed by five-term recurrence relation in the operator-vector form for sinusoidal modulation. A general transmission-line network representation of two-dimensionally periodic medium and multiport network representation of uniform-periodic-medium interface are introduced. Any layered structures cascading with periodic ones can be analyzed. Numerical results based on the established theory are also presented to illustrate characteristics of 2DP medium and structure.

Analysis of planar waveguides with the method of lines and absorbing boundary conditions

The method of lines is extended to analyze planar waveguides with open boundaries. The efficiency of using absorbing boundary conditions is demonstrated by the calculation of the effective permittivity of a single microstrip line. The results show that the boundaries may be placed closer to the guiding structure whereby the discretized area and the corresponding matrices become smaller. >

The method of lines for the analysis of planar waveguides with finite metallization thickness

The method of lines is extended to calculate waveguide structures with finite metallization thickness. The normally used range of metallization thickness is not a limit for the method. Particularly when calculating small or moderate thicknesses, it is possible to derive the dispersion constant with only one computed result. When using the optimal edge parameter, P/sub opt/, for that computation, the deviation from the exact dispersion constant is less than 0.5%. The advantage of the method of lines is that only small line numbers are necessary. Hence, the computing time is very small. >