Terahertz Chiral Optics with Ordered Carbon Nanotube Architectures

The manipulation and control of light's polarization states have significant implications for telecommunications, spectroscopy, sensing, and technology. Engineering the propagation of terahertz (THz) radiation has long been recognized as a challenging endeavor, and it has been the bottleneck that has hindered the full exploitation of the THz spectrum. Recently, it was demonstrated that ultrathin films made with aligned single-wall carbon nanotubes (SWCNTs) can rotate the linear polarization direction of a THz beam both in transmission and reflection configuration [1]. Due to the longitudinal plasmon resonance caused by the finite length of each individual SWCNT, the real and imaginary parts of the optical conductivity of the films, σ, exhibit giant linear anisotropy in the Thz range . However, a single film has an isotropic response for circularly polarized THz radiation. Here, we designed and tested broadband, tunable, and fully reciprocal chiral THz devices fabricated with stacked layers of SWCNT films. Our THz transmission spectroscopy experiments revealed circular dichroism of up to 2.8 degrees. The data fully agrees with our transfer-matrix simulations and Jones matrix formalism calculations.

[1] A. Baydin et al., 2021, Optica, 8, 760.