Enhancement of Self-Collimation Effect in Photonic Crystal Membranes Using Hyperbolic Metamaterials

Hyperbolic metamaterials (HMMs) exhibit high tunability in photonic devices. This study numerically investigates light propagation in photonic crystal (PhC) membranes containing HMMs. The proposed HMM PhC membranes contain square HMM rods, which comprise dielectric (Si) and metallic (Ag) layers. Owing to their property of subwavelength field localization, HMMs can be applied to PhCs to improve tunability and thus enhance the self-collimation (SC) effect of PhCs. The SC points were obtained in the second HMM PhC band, wherein the nearby dispersion curves change significantly. In addition, the effect of the HMM filling factor (i.e., the ratio of the metal-layer to unit-cell thicknesses) on the SC point frequency is studied. Finally, we demonstrate the efficient control of beam behaviors using HMM PhC membranes while considering the nonlinearity of Ag. The findings of this study confirm that high-performance HMM PhC membranes can be employed in nonlinear all-optical switches, filters, tunable lenses, and other integrated optical devices.