Christos Themistos

A finite element method (FEM) based on the vector H-field formulation in conjunction with perturbation techniques is used to study metal-clad microwire waveguides for bio-sensing applications. Sensors are designed to detect DNA hybridization through the change of the effective index and attenuation constant of the waveguide structure. The key parameters, such as effective index, loss coefficient, and spot-sizes are presented and potential sensor applications are discussed.

Finite-element analysis based on the full-vectorial H-field formulation has been established as one of the most powerful and accurate modal solution approaches for optical guided-wave devices. Among the available optical waveguides, those incorporating thin metal layers supporting the surface plasmon modes (SPMs) and coupling of these modes to dielectric modes have recently been proven to be attractive for many applications. In this paper, the H-field approach incorporating the perturbation technique is used in calculating the complex propagation characteristics of silver/polystyrene (PS)-coated hollow glass waveguides for terahertz frequency radiation. The propagation and attenuation characteristics of the SPMs at the metal/dielectric interfaces are presented. The formation of the coupled supermodes and the effect of the PS coating thickness on the attenuation characteristics of these waveguides are also investigated and shown to be critical to their design optimization.

The characterization and optimization of optical microring resonator-based optical filters on deeply etched GaInAsP-Inp waveguides, using the finite element-based beam propagation approach is presented here. Design issues, such as coupling , field evolution, power and phase considerations have also been investigated.

A finite element-based beam propagation approach has been used for the design of a 4 by 4 multimode interference-based device on InP, for wavelength division multiplexing applications, using straight arrayed waveguide gratings with variable width difference.

A wide range of photonic guided-wave devices may be modeled by using rigorous numerical approaches based on the finite element method (FEM). In this work, representative modal solutions for linear, nonlinear, anisotropic, passive and active waveguides are discussed. Photonic devices incorporating several butt-coupled uniform waveguide sections, such as optical modulators, switches, filters, polarizers and spot-size converters are analyzed by using a combination of the least squares boundary residual method and the FEM.