D-FK95-25 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.989212\,\lambda^2}{\lambda^2 - 0.00506591} + \frac{0.0601413\,\lambda^2}{\lambda^2 - 0.0197054} + \frac{0.685378\,\lambda^2}{\lambda^2 - 158.935}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.24 \times 10^{-5} + 2(-5.6 \times 10^{-9})\,\Delta T + 3(-9.96 \times 10^{-12})\,\Delta T^2 + \frac{3.32 \times 10^{-7} + 2(4.01 \times 10^{-12})\,\Delta T}{\lambda - 0.182}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$