H-LAK54 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.20773\,\lambda^2}{\lambda^2 - 0.0176389} + \frac{0.737418\,\lambda^2}{\lambda^2 - 0.000666516} + \frac{1.35749\,\lambda^2}{\lambda^2 - 96.9939}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[5.91 \times 10^{-6} + 2(1.71 \times 10^{-8})\,\Delta T + 3(-2.96 \times 10^{-11})\,\Delta T^2 + \frac{5.65 \times 10^{-7} + 2(5.05 \times 10^{-10})\,\Delta T}{\lambda - 0.196}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$