Background and Tutorials
Symmetric Lossless X Coupler
The X Coupler is a basic component used in many kinds of optical circuits. Here its properties are analysed by theoretical means, and also by detailed simulation of…
VFEM Accuracy and Advantages
As optical systems move towards an integrated platform, the modelling of high refractive index contrast, sub-wavelength dimension…
Plasmon Polaritons – Vector Finite Element Method
The large negative electric permittivities of noble metals permit the design of sub-wavelength optical guiding structures…
Hollow Core Fiber – Vector Finite Element Method
Hollow core fibers guide light by using a photonic bandgap structure in place of a traditional low index cladding material…
Plasmonic Arrays
Plasmonic nano-hole arrays are an interesting avenue of research because of their highly sensitive transmission properties. Incorporating the already strong light-matter interaction of surface plasmons into a periodic structure allows…
Material Models Introduction
One of the main advantages of the FDTD approach is the lack of approximations for the propagating field—light is modeled in its full richness and complexity. The other significant advantage is the great variety of materials that can be consistently modeled within the FDTD context. In this sub-section we make a brief review of some…
Constant Dielectrics
Constant dielectric material is expressed by a complex refractive index value ( ) or relative permittivity value (εr). Here, n is the refractive index indicating the phase velocity informaiton in the medium, while K is called the extinction coefficient, which indicates the amount of absorption loss when the electromagnetic wave propagates through the material. Note that…
Lossy Dielectrics
Before proceeding with a more detailed description it should be emphasized that the fact that in the time domain all the fields (Hx, Ey, Hz) are real quantities. Thus, accounting for loss is possible only through a non-zero conductivity σ of the medium: where Here we have assumed that and corresponds to time-to-frequency domain Fourier transform.…
Lorentz-Drude Model
By Lorentz dispersion materials, we mean materials for which the frequency dependence of the dielectric permittivity can be described by a sum of multiple resonance Lorentzian functions: where ω0m are the resonant frequencies Gm is related to the oscillator strengths Γm is the damping coefficient ε∞ is the permittivity at infinite frequency X0 is the…
