Mixing Rule for Calculating the EffectiveRefractive Index Beyond the Limit of SmallParticles

Considering light transport in disordered media, the medium is often treated as an effective requiring accurate evaluation of refractive index. Because its simplicity, Maxwell-Garnett (MG) mixing rule widely used, although restriction to particles much smaller than wavelength rarely satisfied. Using 3D finite-difference time-domain simulations, we show that MG theory indeed fails for large particles. Systematic investigation size effects reveals index can be instead approximated by a quadratic polynomial whose coefficients are given empirical formula. Hence, simple derived which clearly outperforms established rules composite media containing particles, common condition natural media.