Compact and broadband edge coupler based on non-linear tapers

Abstract

With the increasing integration of optical devices, the requirements for couplers are becoming higher. Nowadays, the couplers not only need to achieve high coupling efficiency, but also achieve a small footprint. In this paper, we propose a broadband and compact edge coupler based on silicon nitride. High coupling efficiency and small footprint can be achieved through a non-linear taper consist of five silicon nitride segments. Aiming at the problem that many relevant parameters introduced by the introduction of five segments and it is difficult to optimize, we select different parameter scanning ranges through the characteristics of different change rates of effective refractive index in different width ranges. So as to design a coupler with high coupling efficiency and small volume. The total length of the coupler is only 91 um, and the coupling efficiency can reach 92.24%. Furthermore, the proposed coupler model has good performance in 1270-1330 nm bandwidth, and the difference between the maximum and minimum coupling efficiency is only 2.48%. At the same time, the 1dB error tolerance of the model can reach 1000 nm.