H-ZLAF56B by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.93771\,\lambda^2}{\lambda^2 - 0.0122004} + \frac{1.5644\,\lambda^2}{\lambda^2 - 122.448} + \frac{0.214506\,\lambda^2}{\lambda^2 - 0.057888}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.63 \times 10^{-6} + 2(1.5 \times 10^{-8})\,\Delta T + 3(-2.72 \times 10^{-11})\,\Delta T^2 + \frac{9.12 \times 10^{-7} + 2(8.32 \times 10^{-10})\,\Delta T}{\lambda - 0.249}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$