H-LAK1 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.964887\,\lambda^2}{\lambda^2 - 91.1939} + \frac{0.468481\,\lambda^2}{\lambda^2 - 0.0205811} + \frac{1.23723\,\lambda^2}{\lambda^2 - 0.00608509}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-4.74 \times 10^{-6} + 2(1.74 \times 10^{-8})\,\Delta T + 3(-3.67 \times 10^{-11})\,\Delta T^2 + \frac{4.92 \times 10^{-7} + 2(2.76 \times 10^{-10})\,\Delta T}{\lambda - 0.181}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$