H-LAFL5 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.26563\,\lambda^2}{\lambda^2 - 102.655} + \frac{1.81325\,\lambda^2}{\lambda^2 - 0.0111615} + \frac{0.173526\,\lambda^2}{\lambda^2 - 0.0541389}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.04 \times 10^{-7} + 2(2.8 \times 10^{-8})\,\Delta T + 3(-1.11 \times 10^{-10})\,\Delta T^2 + \frac{6.56 \times 10^{-7} + 2(-8.41 \times 10^{-10})\,\Delta T}{\lambda - 0.272}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$