H-ZBAF50 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.63432\,\lambda^2}{\lambda^2 - 0.00983161} + \frac{0.988379\,\lambda^2}{\lambda^2 - 102.399} + \frac{0.0611984\,\lambda^2}{\lambda^2 - 0.0499039}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.58 \times 10^{-6} + 2(1.38 \times 10^{-8})\,\Delta T + 3(-3.26 \times 10^{-11})\,\Delta T^2 + \frac{6.19 \times 10^{-7} + 2(5.52 \times 10^{-10})\,\Delta T}{\lambda - 0.183}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$