Figure 5 : The effect of the bend radius on the ZB geometry, for slot = 140 nm, h = 220 nm.

From: Polarisation independent silicon-on-insulator slot waveguides

Figure 5

The black line shows wleft = wright. The bend radius is measured from the centre of the slot. The centre of the bend is in the negative x direction, that is, to the ‘left’ of the left rail. In other words, the left rail is the inner rail and the right rail is the outer rail. Below a bending radius of 20 nm, confinement is less than 0.05 for most combinations of rail widths studied, and hence not shown here. Note that when the outer rail is wider than the inner rail, a larger bending radius leads to requiring a slightly narrower outer rail for ZB. This effect is reversed when the inner rail is wider. Insets (a) and (b) are magnified sections of the graph where the rails are asymmetric.