H-LAF7 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.85621\,\lambda^2}{\lambda^2 - 0.0109606} + \frac{1.38495\,\lambda^2}{\lambda^2 - 114.477} + \frac{0.223526\,\lambda^2}{\lambda^2 - 0.0505772}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.67 \times 10^{-6} + 2(1.23 \times 10^{-8})\,\Delta T + 3(-1.07 \times 10^{-11})\,\Delta T^2 + \frac{6.82 \times 10^{-7} + 2(8.7 \times 10^{-10})\,\Delta T}{\lambda - 0.269}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$