Photonic integrated circuits (PICs) are considered as the way to make photonic systems or subsystems cheap and ubiquitous. PICs still are several orders of magnitude more expensive than their microelectronic counterparts, which has restricted their application to a few niche markets.

No abstract

The rigorous coupled-wave analysis (RCWA) is one of the most successful and widely used methods for modeling periodic optical structures. It yields fast convergence of the electromagnetic far-field and has been adapted to model various optical devices and wave configurations. In this article, we investigate the accuracy with which the electromagnetic near-field can be calculated by using RCWA and explain the observed slow convergence and numerical artifacts from which it suffers, namely unphysical oscillations at material boundaries due to the Gibb's phenomenon. In order to alleviate these shortcomings, we also introduce a mathematical formulation for accurate nearfield calculation in RCWA, for one-and two-dimensional straight and slanted diffraction gratings. This accurate near-field computational approach is tested and evaluated for several representative test-structures and configurations in order to illustrate the advantages provided by the proposed modified formulation of the RCWA.Accurate near-field calculation in the rigorous coupled-wave analysis method

A new method for designing an echelle-type diffraction grating for wavelength division multiplexing (WDM), which is tuned to a single stigmatic point, is introduced. The new grating is defined by the mode and wavelength of operation in a slab waveguide, the position of the waveguides, the order of diffraction, and an arbitrary path, which is called the grating line, upon which individual facets are positioned, blazed, and curved via the outlined algorithm. A systematic design process for echelle gratings (EGs) is presented, covering all the key aspects of this device. A series of rules to improve the performance of any EG WDM device is outlined. A simulated comparison between this device, a standard Rowland grating, and a two stigmatic point grating, was undertaken with the new design performing better and comparably in each case, respectively.

We present an efficient framework for the finite-difference time-domain simulation of real metals. The complex permittivity function of a metal is fitted to experimental data in the frequency domain using a non-linear least squares algorithm. A memory-efficient finite-difference time-domain (FDTD) scheme is presented for the simulation of the dispersive behavior of a metal in the frequency domain. The stability limit for the proposed scheme is determined and compared to the Courant limit. Excellent agreement between our FDTD formulation and the analytical solution for reflections from a thin metal sheet is found.Index Terms-Dispersive media, finite-difference time-domain (FDTD) methods, numerical stability.