H-LAK11 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.0909\,\lambda^2}{\lambda^2 - 0.00492619} + \frac{0.628436\,\lambda^2}{\lambda^2 - 0.0203181} + \frac{1.01438\,\lambda^2}{\lambda^2 - 100.531}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.97 \times 10^{-6} + 2(1.61 \times 10^{-8})\,\Delta T + 3(-3.94 \times 10^{-11})\,\Delta T^2 + \frac{5.45 \times 10^{-7} + 2(2.03 \times 10^{-10})\,\Delta T}{\lambda - 0.199}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$