Yannopapas Vassilios
Department of Physics, National Technical University of Athens, GR-15780 Athens, Greece.
Nanomaterials (Basel). 2015 Mar 19;5(1):376-385. doi: 10.3390/nano5010376.
We show theoretically that photonic crystals consisting of colloidal spheres exhibit unidirectional wave propagation and one-way frequency band gaps without breaking time-reversal symmetry via, e.g., the application of an external magnetic field or the use of nonlinear materials. Namely, photonic crystals with low symmetry such as the monoclinic crystal type considered here as well as with unit cells formed by the heterostructure of different photonic crystals show significant unidirectional electromagnetic response. In particular, we show that the use of scatterers with low refractive-index contrast favors the formation of unidirectional frequency gaps which is the optimal route for achieving unidirectional wave propagation.
我们从理论上证明，由胶体球组成的光子晶体表现出单向波传播和单向频率带隙，而无需通过例如施加外部磁场或使用非线性材料来打破时间反演对称性。也就是说，具有低对称性的光子晶体，如这里所考虑的单斜晶系晶体类型，以及由不同光子晶体的异质结构形成的晶胞，都表现出显著的单向电磁响应。特别是，我们表明，使用具有低折射率对比度的散射体有利于形成单向频率带隙，这是实现单向波传播的最佳途径。
