Enhanced Transmission Properties Of Multiwalled Carbon Nanotube Film In Terahertz Region

While investigating the transmission properties of light through a metal film perforated with subwavelength hole arrays,it have found that the zero-order transmission intensity of such structure can exhibit larger than predicted by standard aperture theory.This extraordinary optical transmission phenomenon,which is generally attributed to resonant excitation of surface plasmon polaritons at the interface,has attracted significant interest due to its potential applications in near-field microscopy and biochemical sensing among others.Firstly,the research background and development situation of the enhanced transmission properties of subwavelength hole arrays are presented in this dissertation.Besides the unique properties of terahertz(THz)wave,the conception and excitation of surface-plasmon polaritons(SPPs)are also described.In this paper,the enhanced THz transmission properties of super-aligned multiwalled carbon nanotube films patterned with one-dimensional subwavelength periodic gratings and two-dimensional periodic rectangular aperture arrays are mainly studied,respectively.The multiwalled carbon nanotube films used in experiments can be directly drawn out from the highly super-aligned MWCNT forests,which were prepared by low pressure chemical vapor deposition(LPCVD).The dielectric properties and anisotropy of the super-aligned MWCNT films can be measured by terahertz time-domain spectroscopy in the frequency range of 0.2-2.5 THz.In the THz region,super-aligned multiwalled carbon nanotube(MWCNT)films can also show a metallic behavior and support SPPs propagating because of their negative real part of dielectric function.And a high degree of agreement was exhibited among the experimental and effective-medium theoretical results.Furthermore,the experimental results of terahertz transmission of the multiwalled carbon nanotube films demonstrate extremely high anisotropy.Thus,the multiwalled carbon nanotubefilms can act as a terahertz polarizer in the frequency rangeAfter this,laser-machining technique is utilized to manufacture gratings and rectangular aperture arrays with two different periods on the MWCNT films,respectively.Based on all of the above results,the experimental and simulation data of the extraordinary transmission of periodic gratings and rectangular aperture arrays in MWCNT films in the THz range are reported.