H-ZLAF75A by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.50615\,\lambda^2}{\lambda^2 - 102.995} + \frac{2.18809\,\lambda^2}{\lambda^2 - 0.0127716} + \frac{0.297956\,\lambda^2}{\lambda^2 - 0.0569662}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.63 \times 10^{-6} + 2(1.36 \times 10^{-8})\,\Delta T + 3(-3.31 \times 10^{-11})\,\Delta T^2 + \frac{9.08 \times 10^{-7} + 2(1.12 \times 10^{-9})\,\Delta T}{\lambda - 0.265}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$