Efficient design of a multilayer structure based on a transmission line model for parallel optical analog computing

Abstract

In this paper, a design method for a multilayer analog computer based on the transmission line model is presented. Here the Green’s function (GF) of the desired mathematical operator is implemented directly in the Fourier domain. The proposed method overcomes major restrictions imposed by previous studies such as slow responses; large architectures arising from the need for additional Fourier sub-blocks; operating only at reflection mode; working at a certain high-frequency range; and most importantly, executing only a single mathematical operation. Despite previous optical multilayer computers, the proposed structure can provide multiple independent operations on impinging fields coming simultaneously from different directions. Due to the generality of the transmission line method, design at any frequency range is possible. Parallel computation is very important for accelerating and miniaturizing wave-based processing architectures, as it could reduce the demand for additional computing blocks. Moreover, using practical dielectric materials could remarkably ease the fabrication process of the analog computer. The versatility of this method is illustrated by a variety of mathematical operations including first- and second-order spatial differentiation and first-order spatial integration. Numerical simulations are also reported for each example, confirming the high-performance of the presented structures.