High efficiency and compact vertical interlayer coupler for silicon nitride-on-silicon photonic platform

Abstract

In recent years, three-dimensional photonic integrated circuits have attracted extensive attention due to the possibility of combining the advantages of many different material systems. However, efficient coupling between multilayers is challenging. In this work, high efficiency and compact vertical interlayer coupler with nonlinear taper was proposed for silicon nitride-on-silicon photonic platform. The coupling efficiency can reach 99.2% at the wavelength of 1550 nm with a small size of 55 µm in length. The crosstalk is below −40 dB in the wavelength range between 1460 nm and 1620 nm. This promotes low-loss and high-dense integration of optical functionalities in hybrid material platforms.