基于石墨烯的可调谐太赫兹光子晶体结构

本文将石墨烯引入到常规光子晶体中构建一种新型光子晶体, 首次从理论上严格导出了决定其能带结构的色散关系, 由于色散关系中石墨烯电导率的存在导致了它具有与常规光子晶体有所不同的特殊光学性质, 我们发现, 随着费米能增大, 低频段能带迅速向高频移动, 而高频段能带移动缓慢, 导致了常规光子晶体没有的能带压缩现象的发生, 究其原因在于石墨烯在低频段电导率迅速变化, 而高频段电导率变化缓慢, 导致能带向高频压缩, 使得光波原先允许频率变成禁止传播, 而禁止频率变成允许传播.

Tunable terahertz photonic crystal structures containing graphene

We introduce graphene into conventional photonic crystals to build new photonic crystal structures, and strictly derive the dispersion relations of the structures based on the electromagnetic boundary conditions and the Maxwell's equations required. The dispersion relations are different from that of the conventional photonic crystals, and the optical properties of the structures may also differ from that of the conventional photonic crystals because of the presence of graphene conductivity in the dispersion relations. By changing the Fermi energy of graphene, the conductivity of it can be changed, the dispersion relations adjusted, the energy band structure altered, and its light propagation manipulated as well. With increasing Fermi energy, the energy band can be transformed from the allowed bands to the prohibited bands and then transformed along the opposite direction to the allowed bands. Because the conductivity changes rapidly in low frequency range, while changes slowly in high frequency range, as the Fermi energy increases, the energy band in the low frequency region will move quickly to higher frequency region, and the energy band in the high frequency region moves slowly, leading to the band compression and mutual conversion between the allowed and the prohibited bands. The larger the Fermi energy, the more obvious the band compression, and the more easy the mutual conversion.