Figure 4
From: Highly efficient dual-level grating couplers for silicon nitride photonics
(a) Comparison of the normalized power density profiles of the optical fibre mode and of the diffracted mode from the dual-level Si–Si\(_3\)N\(_4\) GC with 400 nm thick Si\(_3\)N\(_4\) waveguide; (b) numerically simulated CE at 1550 nm as a function of the separation s between the two layers for the dual-level Si–Si\(_3\)N\(_4\) GC with 400 nm thick Si\(_3\)N\(_4\) waveguide. All the parameters used for these simulations are listed in Table 2 (table row with \(\theta\) = 2\(^\circ\)).
