In order to calculate Fresnel coefficients for layered media, we often need to calculate the angle that light travels inside a material with complex refractive index. Naturally, this is related to the original angle of incidence in air, but how does Snells law work with a complex refractive index? If I come in at $\theta_1$, what is $\theta_2$? Is it still calculated by $n_1 \sin\theta_1 = n_2 \sin\theta_2$ where $n_1$ and $n_2$ are the real parts of the refractive indices? If I treat $n_2$ as complex, I can get a complex angle $\theta_2$. Does this imply there is an evanescent wave alongside a propagating wave?