| Popis: |
The concept of a photonic topological insulator (PTI) was first introduced for photonic crystals, which are periodic structures. Recently, it was suggested that continuous media with broken time-reversal symmetry, and without intrinsic periodicity, such as a magnetized ferrite or a magnetized semiconductor, are topologically nontrivial. A static magnetic field originates a gyrotropic response which makes the material response nonreciprocal. One of the most important aspects of PTIs is their ability to support unidirectional SPPs with unique properties, such as propagation in one direction, protection from backscattering and diffraction upon encountering discontinuities. They are also characterized by an integer Chern invariant, which cannot change except when the underlying momentum space topology of the bulk bands is changed. |
