H-LAF1 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.16155\,\lambda^2}{\lambda^2 - 106.693} + \frac{1.49001\,\lambda^2}{\lambda^2 - 0.00736542} + \frac{0.317836\,\lambda^2}{\lambda^2 - 0.0313945}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1 \times 10^{-6} + 2(2.31 \times 10^{-8})\,\Delta T + 3(-1.6 \times 10^{-10})\,\Delta T^2 + \frac{5.94 \times 10^{-7} + 2(-4.95 \times 10^{-10})\,\Delta T}{\lambda - 0.215}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$