Efficient broadband simulations for thin optical structures

Modeling Curved Carbon Fiber Composite (CFC) Structures in the Transmission-Line Modeling (TLM) Method

“…Transmission lines of lengths 1 l and 2 l are, in this case, made of air but in general can represent any material parameters. The admittance matrix of each layer in the three-layer stack can be expressed as [18], [25]  are the electrical lengths of the two layers of air,…”

“…The disadvantage of this approach is that the Prony method requires a correct choice of the number of poles for good approximation and needs to deal with inverse matrix problems. To avoid using the Prony method, an embedded model for a thin planar layer in the TLM method has recently been reported [18], where the analytical expansions of cotangent and cosecant functions in the admittance matrix of the thin layer are used to efficiently obtain its frequency response.…”

“…Additional constraints on the mesh size are placed when the thickness is much smaller than other physical dimensions of the curved object. In this paper the approach presented in [18] is extended to modeling thin curved panels, which can be composed of ideal or lossy dielectric materials. Embedding of the curved thin panels in the TLM mesh is done firstly, by approximating the panels using a piece-wise linearization and secondly, embedding the linearized segments between adjacent nodes allowing for arbitrary placement between the nodes.…”

“…A three-layer planar stack is introduced to allow for arbitrary model placement between TLM nodes. The frequency response of the three-layer stack is transformed to the time domain by using an inverse Z transform and general digital filter technique as in [18], which results in a slight modification of the TLM algorithm. The structure of the paper is as follows: In section II a short overview of the two-dimensional (2D) TLM method is given together with the description of the embedded model for curved CFC structures.…”

Electro-thermal modelling for plasmonic structures in the TLM method

“…Dispersive and frequency dependent properties are implemented using digital filters methodology (Paul 1998). Traditionally TLM has been used for microwave applications but it has also proved useful at optical frequencies (Janyani et al 2004;Meng et al 2013;Phang et al 2013) The electromagnetic properties of plasma and a range of plasmonic devices such as a Surface Plasmon Polariton Waveguide Bragg Grating (SPP-WBG) and a dielectric surface grating for beam focusing applications have also been modelled in the TLM using the digital filter approach (Ahmed et al 2010;Paul et al 1999).…”