Figure 4 : Understanding the tolerance of ZB slot waveguides.

From: Polarisation independent silicon-on-insulator slot waveguides

Figure 4

(a) How the difference in the effective refractive indices of a straight slot waveguide Δneff = neff, TE − neff, TM is affected when wleft and wright are varied; slot = 140 nm, h = 220 nm, and θ = 0°. The colour bar shows Δneff for a given combination of wleft and wright. In (b) and (c), the solid lines show Δneff = 0.0005 and the dashed lines show Δneff =  ± 0.005; the other parameters which were not varied are kept at the same value as that in (a). (b) The slot size has a negligible effect on tolerance. (c) The tolerance is relaxed when the height is reduced.