Enhanced total internal reflection using low-index nanolattice materials.

Low-index materials are key components in integrated photonics and can enhance index contrast and improve performance. Such materials can be constructed from porous materials, which generally lack mechanical strength and are difficult to integrate. Here we demonstrate enhanced total internal reflection (TIR) induced by integrating robust nanolattice materials with periodic architectures between high-index media. The transmission measurement from the multilayer stack illustrates a cutoff at about a 60° incidence angle, indicating an enhanced light trapping effect through TIR. Light propagation in the nanolattice material is simulated using rigorous coupled-wave analysis and transfer matrix methods, which agrees well with experimental data. The demonstration of the TIR effect in this Letter serves as a first step towards the realization of multilayer devices with nanolattice materials as robust low-index components. These nanolattice materials can find applications in integrated photonics, antireflection coatings, photonic crystals, and low-k dielectric.