H-ZLAF2A by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.76389\,\lambda^2}{\lambda^2 - 0.00842149} + \frac{0.407585\,\lambda^2}{\lambda^2 - 0.0304194} + \frac{1.2702\,\lambda^2}{\lambda^2 - 89.5803}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1.27 \times 10^{-6} + 2(1.49 \times 10^{-8})\,\Delta T + 3(-3.26 \times 10^{-11})\,\Delta T^2 + \frac{6.27 \times 10^{-7} + 2(5.37 \times 10^{-10})\,\Delta T}{\lambda - 0.2}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$