H-ZK4 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.805863\,\lambda^2}{\lambda^2 - 0.0036534} + \frac{0.740367\,\lambda^2}{\lambda^2 - 0.0162979} + \frac{0.904055\,\lambda^2}{\lambda^2 - 95.9876}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[3.08 \times 10^{-7} + 2(1.68 \times 10^{-8})\,\Delta T + 3(-3.77 \times 10^{-11})\,\Delta T^2 + \frac{4.83 \times 10^{-7} + 2(4.1 \times 10^{-10})\,\Delta T}{\lambda - 0.162}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$