Figure 7
From: Highly efficient dual-level grating couplers for silicon nitride photonics
(a) Thickness \(h_2\) which maximizes the CE as a function of the top level refractive index \(n_2\); (b) peak CE at 1550 nm and 1 dB BW as a function of \(n_2\) for dual-level Si\(_x\)N\(_y\)–Si\(_3\)N\(_4\) GC for a 400 nm thick Si\(_3\)N\(_4\) platform.
