H-ZK14 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.821911\,\lambda^2}{\lambda^2 - 0.0036966} + \frac{0.995367\,\lambda^2}{\lambda^2 - 97.9765} + \frac{0.708381\,\lambda^2}{\lambda^2 - 0.015941}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[3.66 \times 10^{-7} + 2(1.7 \times 10^{-8})\,\Delta T + 3(-3.14 \times 10^{-11})\,\Delta T^2 + \frac{3.59 \times 10^{-7} + 2(3.53 \times 10^{-10})\,\Delta T}{\lambda - 0.219}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$