Design of an Arrayed Waveguide Grating with flat spectral response

摘要

Arrayed Waveguide Gratings (AWGs) are key components in current and future optical network realizations. In order to prevent the need of accurate wavelength control the transfer function of the AWG should ideally have a rectangular shape. Several techniques have been proposed in order to flatten the Gaussian-like transfer function of the conventional AWG. In this paper we propose a new technique is based on the modification of the arrayed waveguide lengths and their positions on the Free Propagation Regions. The above technique is similar to the deterministic tapering technique used in the design of antenna arrays, since the spatial transfer function of the latter has the same characteristics as the spectral transfer function of an AWG. Therefore, problem is reduced to that of matching the integral of a sinc function with a discrete step function and the optimal waveguide lengths are obtained by solving a set of equations numerically. The performance of this technique (in terms of transfer function flatness, sidelobe level and insertion losses compared to a conventional AWG) depends on the values given to several initial design parameters related to the AWG geometry. The results obtained show that it is feasible to fabricate AWGs with rectangular tra nsfer function with proper adjustment of certain structural parameters.