High-efficiency interlayer coupler on silicon nitride

Abstract

In this paper, we propose a low-loss and high fabrication tolerance polarization insensitive interlayer coupler on silicon nitride. The interlayer coupler has an insertion loss of 0.31 dB for the TE mode and 0.03 dB for the TM mode. A pair of nonlinear inverse tapers are used to reduce the device length and achieve low insertion loss. The insertion loss variation is only 0.22 dB for the TE mode and 0.18 dB for the TM mode over the 1500 nm to 1600 nm working bandwidth.