Tunable Giant Ultraviolet Circular Dichroism in Wafer-Scale Carbon Nanotube Architectures with Engineered Chirality

Controlling the dissymmetric interaction of circularly polarized light with solid-state materials is required for chiral quantum photonic systems. The extraordinarily strong 1D quantum confinement of electrons and photons in carbon nanotubes (CNTs) leads to robust quantum phenomena, ideally suited for developing high-operating-temperature devices to generate, modulate, and detect quantum light. Although circular dichroism has been observed in enantiomer-enriched chiral CNT suspensions, there have been no reports on macroscopic assemblies of ordered CNTs with engineered chiroptical properties. Here, we demonstrate tunable, giant, and structure-induced deep-ultraviolet circular dichroism ellipticity in wafer-scale films of ordered racemic CNTs prepared using two approaches: mechanical-rotation-assisted vacuum filtration and 3D chiral stacking of aligned CNTs. We are able to engineer the chirality, including the strength and sign of circular dichroism, by adjusting the rotation forces and the twist angles, respectively, in the two approaches. These experimental observations fully agree with both transfer-matrix calculations and full-wave electromagnetic numerical simulations.