S-LAL7 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{0.916121\,\lambda^2}{\lambda^2 - 0.0039589} + \frac{0.765948\,\lambda^2}{\lambda^2 - 0.0167547} + \frac{1.27745\,\lambda^2}{\lambda^2 - 110.763}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[5.43 \times 10^{-8} + 2(1.3 \times 10^{-8})\,\Delta T + 3(-3.43 \times 10^{-11})\,\Delta T^2 + \frac{3.49 \times 10^{-7} + 2(4.29 \times 10^{-10})\,\Delta T}{\lambda - 0.237}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$