S-NSL36 by Ohara

$$n(\lambda) = \sqrt{1 + \frac{1.09666\,\lambda^2}{\lambda^2 - 0.00667491} + \frac{0.16899\,\lambda^2}{\lambda^2 - 0.0336095} + \frac{1.20581\,\lambda^2}{\lambda^2 - 141.669}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[6.73 \times 10^{-7} + 2(1.17 \times 10^{-8})\,\Delta T + 3(-4.11 \times 10^{-11})\,\Delta T^2 + \frac{5.17 \times 10^{-7} + 2(5.13 \times 10^{-10})\,\Delta T}{\lambda - 0.241}\right] \Delta T = T - T_0, \quad T_0 = 25\,°\text{C}$$