L-LAL13 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.17776\,\lambda^2}{\lambda^2 - 0.00557618} + \frac{0.634591\,\lambda^2}{\lambda^2 - 0.0206821} + \frac{1.20436\,\lambda^2}{\lambda^2 - 99.6323}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[1.27 \times 10^{-6} + 2(9.45 \times 10^{-9})\,\Delta T + 3(-3.49 \times 10^{-11})\,\Delta T^2 + \frac{5.82 \times 10^{-7} + 2(6.14 \times 10^{-10})\,\Delta T}{\lambda - 0.192}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$