D-ZLAF67-25 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.36012\,\lambda^2}{\lambda^2 - 103.58} + \frac{2.09601\,\lambda^2}{\lambda^2 - 0.011038} + \frac{0.333537\,\lambda^2}{\lambda^2 - 0.0449414}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[3.22 \times 10^{-6} + 2(1.64 \times 10^{-8})\,\Delta T + 3(-4.25 \times 10^{-11})\,\Delta T^2 + \frac{8.62 \times 10^{-7} + 2(7.87 \times 10^{-10})\,\Delta T}{\lambda - 0.235}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$