Near-Zero-Refractive-Index Structure at Optical Frequencies

Figure 3

The real part of the effective refractive index, 𝑛, versus the frequency for different dielectric core thicknesses. In (a), 𝑡=30 nm, (b) 40 nm, (c) 50 nm, and (d) 60 nm.

(a)

(b)

(c)

(d)