H-ZLAF68NB by CDGM

$$n(\lambda) = \sqrt{1 + \frac{2.08929\,\lambda^2}{\lambda^2 - 0.0106315} + \frac{0.347248\,\lambda^2}{\lambda^2 - 0.0414144} + \frac{1.58625\,\lambda^2}{\lambda^2 - 120.088}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-7.01 \times 10^{-7} + 2(1.34 \times 10^{-8})\,\Delta T + 3(-1.92 \times 10^{-11})\,\Delta T^2 + \frac{7.62 \times 10^{-7} + 2(5.26 \times 10^{-10})\,\Delta T}{\lambda - 0.235}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$