Prediction of Effective Optical Properties of Anisotropic Composites Beyond the Quasistatic Limit

The preponderance of previous treatments to predict the effective dielectric constant of composites apply to the quasistatic (long-wavelength) regime. Recently, Torquato and Kim [PRX11, 021002 (2021)] derived the exact nonlocal "strong-contrast" expansion formalism for the effective dynamic dielectric constant tensor for general two-phase microstructures that is applicable from very long to intermediate wavelengths. While accurate approximation formulas were obtained for isotropic media previously, here we extract for the first time corresponding formulas for microstructures of various symmetries in three dimensions. Similar to the previous approximation, these approximations are rational functions that depend on certain integrals involving the two-point correlation function or its Fourier counterpart (i.e., spectral density), and hence, account for the multiple scattering to all orders. We apply our new formulas to a variety of hyperuniform and nonhyperuniform disordered anisotropic models. Our theoretical results compare favorably to full-waveform simulations.