H-QF8 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.127874\,\lambda^2}{\lambda^2 - 0.0424546} + \frac{1.20201\,\lambda^2}{\lambda^2 - 0.00811386} + \frac{0.929469\,\lambda^2}{\lambda^2 - 109.833}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.28 \times 10^{-6} + 2(1.48 \times 10^{-8})\,\Delta T + 3(-8.66 \times 10^{-11})\,\Delta T^2 + \frac{5.08 \times 10^{-7} + 2(1.15 \times 10^{-10})\,\Delta T}{\lambda - 0.282}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$