H-LAF51 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.16092\,\lambda^2}{\lambda^2 - 102.914} + \frac{1.53442\,\lambda^2}{\lambda^2 - 0.00759736} + \frac{0.293142\,\lambda^2}{\lambda^2 - 0.0338072}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.02 \times 10^{-6} + 2(1.89 \times 10^{-8})\,\Delta T + 3(-1.3 \times 10^{-10})\,\Delta T^2 + \frac{4.46 \times 10^{-7} + 2(1.77 \times 10^{-10})\,\Delta T}{\lambda - 0.281}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$