Birefringent ceramic-based 1D photonic crystals enabling omnidirectional reflection and tunable multifunctional polarization control

This study presents the design and analysis of birefringent one-dimensional photonic crystals composed of anisotropic ceramic layers for multifunctional optical applications. The structure leverages polarization- and angle-dependent refractive index behavior of birefringent ceramics to achieve tunable photonic bandgap characteristics under both TE and TM polarizations. For TM polarization, the strong angular dependence of the effective refractive index enables engineered omnidirectional reflection bands, angle-selective polarization filters, and broadband TM-pass polarizer. Incorporating both uniaxial and biaxial ceramics enhances anisotropy, improving spectral tunability and polarization separation. The proposed design achieves a high polarization extinction ratio >30 dB and low insertion loss <1.5 dB across a broad angular range. Broadband polarization-selective windows are demonstrated in the telecommunication range (850 nm band to L band), with the effective Brewster condition realized using a high-index ambient medium. These results establish birefringent ceramic-based 1D PCs as promising candidates for compact, angle-tunable, and polarization-sensitive optical devices.