Texture and light-induced anisotropic terahertz properties of free-standing single-walled carbon nanotube films with random networks

We present an anisotropic property investigation of the free-standing single-walled carbon nanotube (SWCNT) random networks by terahertz time-domain spectroscopy (THz-TDS). Strongly anisotropic transmission in the spectral region 0.3-2.5 THz is observed. The experimental observation implies that our pristine SWCNT networks show preferential order in micrometer scale, which are attributed to the formation of the texture pattern. Modulation of this exceptional anisotropy by mechanical stretching and light illuminating indicates that the anisotropic response can be enhanced. The light-induced anisotropic property shows a hyperbolic tangent dependence with the pump power. The results suggest the potential applications and manipulations of SWCNT networks for THz electro-optical and polarized devices.