H-ZLAF66GT by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.233019\,\lambda^2}{\lambda^2 - 0.0537435} + \frac{1.9066\,\lambda^2}{\lambda^2 - 0.0114337} + \frac{1.37147\,\lambda^2}{\lambda^2 - 110.631}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.89 \times 10^{-6} + 2(1.64 \times 10^{-8})\,\Delta T + 3(-1.41 \times 10^{-10})\,\Delta T^2 + \frac{8.7 \times 10^{-7} + 2(1.01 \times 10^{-9})\,\Delta T}{\lambda - 0.245}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$