Figure 1: (a) Schematic view of CNT for an application of elastic wave filter in the particular frequency around 36 THz. (b) Phonon band structures of CNTs with chirality (left) and (right). We see that CNT exhibits no phononic bandgap up to 50 THz, while CNT has a phononic bandgap around 36 THz, corresponding to meV. Here and are unit cell lengths for CNT and CNT, respectively.