Table 2. Waveguide Mode Indices of Coaxial Metamaterial (Table 1, Sample 1) for Six Different Wavelengths^a.

	waveguide mode index
wavelength (nm)	single-coax dispersion	hexagonal array of coaxes
400	2.35	2.17
440	0.11	–0.12
460	–1.63	–1.49
500	–4.67	–4.74
600
700	10.54	13.61

^aData are derived from calculated single-coax dispersion and H_y-field plots obtained with FDTD simulations. At λ = 600 nm the index is undefined since there is no propagating mode at this wavelength, making it impossible to extract the index using the method described above.