Exciton-plasmon coupling in ultrathin periodically aligned carbon nanotube arrays.*

We study theoretically the in-plane electromagnetic response and the exciton-plasmon interactions for an experimentally feasible carbon nanotube (CN) film systems composed of parallel aligned periodic semiconducting CN arrays embedded in an ultrathin finite-thickness dielectric[1,2]. For homogeneous single-chirality CN films, the intertube coupling and the thermal broadening bring the exciton and interband plasmon resonances closer together. These resonances can overlap due to the inhomogeneous broadening for films composed of array mixtures with a slight CN diameter/chirality distribution. In such systems the real part of the response function is negative for a broad range of energies (negative refraction band), and the CN film behaves as a hyperbolic metamaterial. We also show that for a properly fabricated two-component utrathin CN film, by varying the relative weights of the two constituent CN array components one can tune the optical absorption profile to make the film transmit or absorb light in the neighborhood of an exciton absorption resonance on-demand. – [1]C.M.Adhikari and I.V.Bondarev, MRS Advances, doi10.1557/adv.2020.234; [2]C.M.Adhikari and I.V.Bondarev, arXiv2010.00139.