H-ZLAF75B by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.322804\,\lambda^2}{\lambda^2 - 0.0552627} + \frac{2.16371\,\lambda^2}{\lambda^2 - 0.0124574} + \frac{1.59868\,\lambda^2}{\lambda^2 - 108.246}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.36 \times 10^{-6} + 2(1.27 \times 10^{-8})\,\Delta T + 3(-2.37 \times 10^{-11})\,\Delta T^2 + \frac{9.1 \times 10^{-7} + 2(1.21 \times 10^{-9})\,\Delta T}{\lambda - 0.262}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$