Far-zone spectral modulation by a semi-soft anisotropic hollow deterministic medium: decoupling of inner and outer structural information

The spectral modulation of polychromatic light waves with a Gaussian spectral profile upon scattering from a semi-soft anisotropic hollow deterministic medium is theoretically and numerically investigated. By deriving analytical expressions for the far-zone spectral density, we systematically analyze the critical conditions inducing spectral anomalies, specifically redshift, blueshift, and spectral switches. Numerical simulations reveal that these spectral switches exhibit robust azimuthal selectivity, strictly governed by the medium’s three-dimensional anisotropy. A pivotal finding is that the structural dimensions parallel to the observation plane dominate the primary spectral response, whereas the inner hollow core and longitudinal structure uniquely modulate higher-order spectral features at large scattering angles. Crucially, we demonstrate that this specific hollow configuration enables the effective decoupling of inner and outer structural information. These insights provide a rigid theoretical framework for the non-invasive characterization of complex multi-layered particles, offering new degrees of freedom for the precise control of far-field spectral properties.