Chung-Ping Chen

Simulations of Dielectric and Plasmonic Waveguide-Coupled Ring Resonators Using the Legendre Pseudospectral Time-Domain Method

The accurate Legendre pseudospectral time-domain (PSTD) method is applied in this paper to the study of optical behaviors of 2-D dielectric and plasmonic waveguide-coupled ring resonators. Based on its inherent multidomain scheme with curvilinear-quadrilateral subdomain partitioning, the PSTD method possesses superior advantage in fulfilling field continuity conditions across material interfaces, which provides better numerical handling upon circular or even more complicated ring structures. Accordingly, investigations of several plasmonic nanoring resonators of different shapes with surface plasmon polariton (SPP) waves propagating on the metal/dielectric/metal waveguides are made with the aids of a well-fitted Drude-Lorentz material-dispersion model through analyzing their characteristics in the near-infrared and visible parts of the light spectrum. Especially, the racetrack-shaped ring is carefully designed with optimized track length to avoid the over- or under-coupling problem between the ring and input waveguides and, thus, achieve excellent spectral performance.

High-Accuracy Waveguide Leaky-Mode Analysis Using a Multidomain Pseudospectral Frequency-Domain Method Incorporated With Stretched Coordinate PML

A recently developed pseudospectral frequency-domain (PSFD) method employing a penalty scheme is further incorporated with stretched coordinate perfectly matched layers (PMLs) in order to solve waveguide leaky modes. Several standard leaky-mode slab and circular waveguides, including the W-type and M-type ones, are examined first by solving their complex effective indexes and field profiles, showing that the PSFD method achieves computational accuracy on the order of 10-15. Then, this high-accuracy solver is used to analyze waveguide structures with more complicated geometries, such as the leaky six-air-hole fiber, for which self convergence of accuracy in calculated effective indexes is demonstrated to be on the orders of 10-14 , and two rectilineal waveguides with sharp corners, i.e., the rib waveguide and the photonic wire. Comparison of the PSFD method obtained results for these more complicated waveguide structures with those from other methods in the literature is presented and discussed.

A High-Accuracy Multidomain Legendre Pseudospectral Frequency-Domain Method With Penalty Scheme for Solving Scattering and Coupling Problems of Nano-Cylinders

A new multidomain pseudospectral frequency-domain (PSFD) method based on the Legendre polynomials with penalty scheme is developed for numerically modeling electromagnetic wave scattering problems. The primary aim of the proposed method is to more accurately analyzing scattering and coupling problems in plasmonics, in which optical waves interact with nanometer-sized metallic structures. Using light scattering by a silver circular cylinder as a first example, the formulated method is demonstrated to achieve numerical accuracy in near-field calculations on the order of 10-9 with respect to a unity field strength of the incident wave with excellent exponentially convergent behavior in numerical accuracy. Then, scattering by a dielectric square cylinder and that by several coupled metallic structures involving circular cylinders, square cylinders, or dielectric coated cylinders are examined to provide high-accuracy coupled near-field results.

Numerical investigation of light scattering by coupled plasmonic nanospheres using a high-accuracy multidomain Legendre pseudospectral time-domain method

A high-numerical-accuracy multidomain Legendre pseudospectral time-domain (PSTD) method is utilized to study the three-dimensional problem of light scattering by coupled metallic nanospheres and associated plasmonic resonances. With the multidomain technique, the simulation environment is partitioned into curvilinear hexahedral subdomains that well match the geometrical profile and material interfaces, which is an essential treatment to assure numerical accuracy, in particular, in near-field calculations. Cross sections are accurately calculated for studying the effects of different sphere radii and spacings. Interactions between two silver spheres are investigated for different incident wave propagation directions and polarizations. Electric near fields at plasmon resonances are examined.

Modelling plasmonic waveguide resonators using pseudospectral methods

A high-order accurate Legendre pseudospectral time-domain (PSTD) method has been established for accurate analyses and simulations of electromagnetic problems, in particular, plasmonics related problems. Here it is employed to simulate transmission characteristics of two-dimensional plasmonic ring resonators based on the metal/insulator/metal (MIM) waveguide structure. The formulated PSTD method is based on a penalty scheme and a multidomain approach. The same penalty scheme is used to derive a pseudospectral frequency-domain (PSFD) method which offers an alternative technique to analyze the same resonators.

High-Accuracy Calculations of Light Scattering by Plasmonic Cylinders Using the Legendre Pseudospectral Frequency-Domain (PSFD) Method

A high-order accurate pseudospectral frequency-domain (PSFD) method is used to analyze light scattering by plasmonic cylinders. Field coupling and enhancement within the gap of close spaced cylinders are examined.

A legendre pseudospectral frequency-domain method for solving Maxwell's equations

A pseudospectral frequency-domain (PSFD) method with multi-domain approach and based on Legendre polynomials is developed for solving Maxwells equations. One aim of the proposed method is to more accurately model problems in plasmonics in which electromagnetic waves interact with metallic structures at optical frequencies. Calculation of light scattering by a silver circular cylinder demonstrates that the accuracy of the obtained field strength can be as good as on the order of 10−9 of the incident field strength.

Electromagnetic simulations of 2D optical microring resonators using the multidomain Legendre pseudospectral time-domain method

The high-accuracy pseudospectral time-domain (PSTD) method is utilized to simulate electromagnetic responses of two-dimensional (2D) optical microring resonators. Besides its inherent spectral convergence in accuracy, the PSTD method using multidomain approach with curvilinear-quadrilateral subdomain partitioning possesses superior advantage in fulfilling field continuity conditions across material interfaces. And it should provide better results than the FDTD method simulations for optical waveguide resonators involving circular rings since the stair-casing approximation as often employed in the latter is avoided.

A multidomain Legendre pseudospectral frequency-domain method with penalty scheme for solving maxwell's equations

A new multidomain pseudospectral frequency-domain (PSFD) method based on Legendre polynomials with a penalty scheme for studying electromagnetic wave scattering is presented. Scattered field calculation with accuracy on the order of 10−9 is obtained for a circular plasmonic cylinder. The method is further applied to demonstrate the scattering by a dielectric rectangular cylinder with sharp corners and by multiple circular plasmonic cylinders.