Figure 2
From: Transport of Photonic Bloch Wave in Arrayed Two-Level Atoms
Dispersion. (a) Dispersion relations (the real part k ω a/π versus ω/ν [solid line], and the imaginary part κ ω a/π versus ω/ν [dashed line]) of photonic field propagating (outgoingly) in an array of two-level atoms. Energy gap exists and it is where κ ω  > 0. The dotted line is the dispersion relation of free photon. Here we choose N = 100, g2/a = 0.01, ν = 0.25π, and \(\delta =3\ast {10}^{-3}\nu \). The y-axis is in unit of ka/π, and the x-axis is in unit of ω/ν; both of them are dimensionless. (b) The index of refraction n is shown in the inset. The x-axis is λ/λ0, with λ0 the wavelength at the resonant angular frequency ν. The two dotted lines show where the energy gap appears between 0.918λ0 & 1.094λ0.
